gecko/content/base/src/nsObjectLoadingContent.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// vim:set et cin sw=2 sts=2:
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla <object> loading code.
 *
 * The Initial Developer of the Original Code is
 * Christian Biesinger <cbiesinger@web.de>.
 * Portions created by the Initial Developer are Copyright (C) 2005
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Justin Dolske <dolske@mozilla.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/*
 * A base class implementing nsIObjectLoadingContent for use by
 * various content nodes that want to provide plugin/document/image
 * loading functionality (eg <embed>, <object>, <applet>, etc).
 */

// Interface headers
#include "imgILoader.h"
#include "nsEventDispatcher.h"
#include "nsIContent.h"
#include "nsIDocShell.h"
#include "nsIDocument.h"
#include "nsIDOMDataContainerEvent.h"
#include "nsIDOMDocument.h"
#include "nsIDOMEventTarget.h"
#include "nsIExternalProtocolHandler.h"
#include "nsEventStates.h"
#include "nsIObjectFrame.h"
#include "nsIPluginDocument.h"
#include "nsPluginHost.h"
#include "nsIPresShell.h"
#include "nsIPrivateDOMEvent.h"
#include "nsIScriptGlobalObject.h"
#include "nsIScriptSecurityManager.h"
#include "nsIStreamConverterService.h"
#include "nsIURILoader.h"
#include "nsIURL.h"
#include "nsIWebNavigation.h"
#include "nsIWebNavigationInfo.h"
#include "nsIScriptChannel.h"
#include "nsIBlocklistService.h"
#include "nsIAsyncVerifyRedirectCallback.h"

#include "nsPluginError.h"

// Util headers
#include "prlog.h"

#include "nsAutoPtr.h"
#include "nsCURILoader.h"
#include "nsContentPolicyUtils.h"
#include "nsContentUtils.h"
#include "nsDocShellCID.h"
#include "nsGkAtoms.h"
#include "nsThreadUtils.h"
#include "nsNetUtil.h"
#include "nsMimeTypes.h"
#include "nsStyleUtil.h"
#include "nsGUIEvent.h"
#include "nsUnicharUtils.h"

// Concrete classes
#include "nsFrameLoader.h"

#include "nsObjectLoadingContent.h"
#include "mozAutoDocUpdate.h"
#include "nsIContentSecurityPolicy.h"
#include "nsIChannelPolicy.h"
#include "nsChannelPolicy.h"

#ifdef PR_LOGGING
static PRLogModuleInfo* gObjectLog = PR_NewLogModule("objlc");
#endif

#define LOG(args) PR_LOG(gObjectLog, PR_LOG_DEBUG, args)
#define LOG_ENABLED() PR_LOG_TEST(gObjectLog, PR_LOG_DEBUG)

class nsAsyncInstantiateEvent : public nsRunnable {
public:
  // This stores both the content and the frame so that Instantiate calls can be
  // avoided if the frame changed in the meantime.
  nsObjectLoadingContent *mContent;
  nsWeakFrame             mFrame;
  nsCString               mContentType;
  nsCOMPtr<nsIURI>        mURI;

  nsAsyncInstantiateEvent(nsObjectLoadingContent* aContent,
                          nsIFrame* aFrame,
                          const nsCString& aType,
                          nsIURI* aURI)
    : mContent(aContent), mFrame(aFrame), mContentType(aType), mURI(aURI)
  {
    static_cast<nsIObjectLoadingContent *>(mContent)->AddRef();
  }

  ~nsAsyncInstantiateEvent()
  {
    static_cast<nsIObjectLoadingContent *>(mContent)->Release();
  }

  NS_IMETHOD Run();
};

NS_IMETHODIMP
nsAsyncInstantiateEvent::Run()
{
  // Check if we've been "revoked"
  if (mContent->mPendingInstantiateEvent != this)
    return NS_OK;
  mContent->mPendingInstantiateEvent = nsnull;

  // Make sure that we still have the right frame (NOTE: we don't need to check
  // the type here - GetExistingFrame() only returns object frames, and that
  // means we're a plugin)
  // Also make sure that we still refer to the same data.
  nsIObjectFrame* frame = mContent->
    GetExistingFrame(nsObjectLoadingContent::eFlushContent);

  nsIFrame* objectFrame = nsnull;
  if (frame) {
    objectFrame = do_QueryFrame(frame);
  }

  if (objectFrame &&
      mFrame.GetFrame() == objectFrame &&
      mContent->mURI == mURI &&
      mContent->mContentType.Equals(mContentType)) {
    if (LOG_ENABLED()) {
      nsCAutoString spec;
      if (mURI) {
        mURI->GetSpec(spec);
      }
      LOG(("OBJLC [%p]: Handling Instantiate event: Type=<%s> URI=%p<%s>\n",
           mContent, mContentType.get(), mURI.get(), spec.get()));
    }

    nsresult rv = mContent->Instantiate(frame, mContentType, mURI);
    if (NS_FAILED(rv)) {
      mContent->Fallback(PR_TRUE);
    }
  } else {
    LOG(("OBJLC [%p]: Discarding event, data changed\n", mContent));
  }

  return NS_OK;
}

/**
 * A task for firing PluginNotFound and PluginBlocklisted DOM Events.
 */
class nsPluginErrorEvent : public nsRunnable {
public:
  nsCOMPtr<nsIContent> mContent;
  PluginSupportState mState;

  nsPluginErrorEvent(nsIContent* aContent, PluginSupportState aState)
    : mContent(aContent),
      mState(aState)
  {}

  ~nsPluginErrorEvent() {}

  NS_IMETHOD Run();
};

NS_IMETHODIMP
nsPluginErrorEvent::Run()
{
  LOG(("OBJLC []: Firing plugin not found event for content %p\n",
       mContent.get()));
  nsString type;
  switch (mState) {
    case ePluginUnsupported:
      type = NS_LITERAL_STRING("PluginNotFound");
      break;
    case ePluginDisabled:
      type = NS_LITERAL_STRING("PluginDisabled");
      break;
    case ePluginBlocklisted:
      type = NS_LITERAL_STRING("PluginBlocklisted");
      break;
    case ePluginOutdated:
      type = NS_LITERAL_STRING("PluginOutdated");
      break;
    default:
      return NS_OK;
  }
  nsContentUtils::DispatchTrustedEvent(mContent->GetDocument(), mContent,
                                       type, PR_TRUE, PR_TRUE);

  return NS_OK;
}

/**
 * A task for firing PluginCrashed DOM Events.
 */
class nsPluginCrashedEvent : public nsRunnable {
public:
  nsCOMPtr<nsIContent> mContent;
  nsString mPluginDumpID;
  nsString mBrowserDumpID;
  nsString mPluginName;
  nsString mPluginFilename;
  PRBool mSubmittedCrashReport;

  nsPluginCrashedEvent(nsIContent* aContent,
                       const nsAString& aPluginDumpID,
                       const nsAString& aBrowserDumpID,
                       const nsAString& aPluginName,
                       const nsAString& aPluginFilename,
                       PRBool submittedCrashReport)
    : mContent(aContent),
      mPluginDumpID(aPluginDumpID),
      mBrowserDumpID(aBrowserDumpID),
      mPluginName(aPluginName),
      mPluginFilename(aPluginFilename),
      mSubmittedCrashReport(submittedCrashReport)
  {}

  ~nsPluginCrashedEvent() {}

  NS_IMETHOD Run();
};

NS_IMETHODIMP
nsPluginCrashedEvent::Run()
{
  LOG(("OBJLC []: Firing plugin crashed event for content %p\n",
       mContent.get()));

  nsCOMPtr<nsIDOMDocument> domDoc =
    do_QueryInterface(mContent->GetDocument());
  if (!domDoc) {
    NS_WARNING("Couldn't get document for PluginCrashed event!");
    return NS_OK;
  }

  nsCOMPtr<nsIDOMEvent> event;
  domDoc->CreateEvent(NS_LITERAL_STRING("datacontainerevents"),
                      getter_AddRefs(event));
  nsCOMPtr<nsIPrivateDOMEvent> privateEvent(do_QueryInterface(event));
  nsCOMPtr<nsIDOMDataContainerEvent> containerEvent(do_QueryInterface(event));
  if (!privateEvent || !containerEvent) {
    NS_WARNING("Couldn't QI event for PluginCrashed event!");
    return NS_OK;
  }

  event->InitEvent(NS_LITERAL_STRING("PluginCrashed"), PR_TRUE, PR_TRUE);
  privateEvent->SetTrusted(PR_TRUE);
  privateEvent->GetInternalNSEvent()->flags |= NS_EVENT_FLAG_ONLY_CHROME_DISPATCH;
  
  nsCOMPtr<nsIWritableVariant> variant;

  // add a "pluginDumpID" property to this event
  variant = do_CreateInstance("@mozilla.org/variant;1");
  if (!variant) {
    NS_WARNING("Couldn't create pluginDumpID variant for PluginCrashed event!");
    return NS_OK;
  }
  variant->SetAsAString(mPluginDumpID);
  containerEvent->SetData(NS_LITERAL_STRING("pluginDumpID"), variant);

  // add a "browserDumpID" property to this event
  variant = do_CreateInstance("@mozilla.org/variant;1");
  if (!variant) {
    NS_WARNING("Couldn't create browserDumpID variant for PluginCrashed event!");
    return NS_OK;
  }
  variant->SetAsAString(mBrowserDumpID);
  containerEvent->SetData(NS_LITERAL_STRING("browserDumpID"), variant);

  // add a "pluginName" property to this event
  variant = do_CreateInstance("@mozilla.org/variant;1");
  if (!variant) {
    NS_WARNING("Couldn't create pluginName variant for PluginCrashed event!");
    return NS_OK;
  }
  variant->SetAsAString(mPluginName);
  containerEvent->SetData(NS_LITERAL_STRING("pluginName"), variant);

  // add a "pluginFilename" property to this event
  variant = do_CreateInstance("@mozilla.org/variant;1");
  if (!variant) {
    NS_WARNING("Couldn't create pluginFilename variant for PluginCrashed event!");
    return NS_OK;
  }
  variant->SetAsAString(mPluginFilename);
  containerEvent->SetData(NS_LITERAL_STRING("pluginFilename"), variant);

  // add a "submittedCrashReport" property to this event
  variant = do_CreateInstance("@mozilla.org/variant;1");
  if (!variant) {
    NS_WARNING("Couldn't create crashSubmit variant for PluginCrashed event!");
    return NS_OK;
  }
  variant->SetAsBool(mSubmittedCrashReport);
  containerEvent->SetData(NS_LITERAL_STRING("submittedCrashReport"), variant);

  nsEventDispatcher::DispatchDOMEvent(mContent, nsnull, event, nsnull, nsnull);
  return NS_OK;
}

class AutoNotifier {
  public:
    AutoNotifier(nsObjectLoadingContent* aContent, PRBool aNotify) :
      mContent(aContent), mNotify(aNotify) {
        mOldType = aContent->Type();
        mOldState = aContent->ObjectState();
    }
    ~AutoNotifier() {
      if (mNotify) {
        mContent->NotifyStateChanged(mOldType, mOldState, PR_FALSE);
      }
    }

    /**
     * Send notifications now, ignoring the value of mNotify. The new type and
     * state is saved, and the destructor will notify again if mNotify is true
     * and the values changed.
     */
    void Notify() {
      NS_ASSERTION(mNotify, "Should not notify when notify=false");

      mContent->NotifyStateChanged(mOldType, mOldState, PR_TRUE);
      mOldType = mContent->Type();
      mOldState = mContent->ObjectState();
    }

  private:
    nsObjectLoadingContent*            mContent;
    PRBool                             mNotify;
    nsObjectLoadingContent::ObjectType mOldType;
    nsEventStates                      mOldState;
};

/**
 * A class that will automatically fall back if a |rv| variable has a failure
 * code when this class is destroyed. It does not notify.
 */
class AutoFallback {
  public:
    AutoFallback(nsObjectLoadingContent* aContent, const nsresult* rv)
      : mContent(aContent), mResult(rv), mPluginState(ePluginOtherState) {}
    ~AutoFallback() {
      if (NS_FAILED(*mResult)) {
        LOG(("OBJLC [%p]: rv=%08x, falling back\n", mContent, *mResult));
        mContent->Fallback(PR_FALSE);
        if (mPluginState != ePluginOtherState) {
          mContent->mFallbackReason = mPluginState;
        }
      }
    }

    /**
     * This should be set to something other than ePluginOtherState to indicate
     * a specific failure that should be passed on.
     */
     void SetPluginState(PluginSupportState aState) {
       NS_ASSERTION(aState != ePluginOtherState, "Should not be setting ePluginOtherState");
       mPluginState = aState;
     }
  private:
    nsObjectLoadingContent* mContent;
    const nsresult* mResult;
    PluginSupportState mPluginState;
};

/**
 * A class that automatically sets mInstantiating to false when it goes
 * out of scope.
 */
class AutoSetInstantiatingToFalse {
  public:
    AutoSetInstantiatingToFalse(nsObjectLoadingContent* objlc) : mContent(objlc) {}
    ~AutoSetInstantiatingToFalse() { mContent->mInstantiating = PR_FALSE; }
  private:
    nsObjectLoadingContent* mContent;
};

// helper functions
static PRBool
IsSupportedImage(const nsCString& aMimeType)
{
  imgILoader* loader = nsContentUtils::GetImgLoader();
  if (!loader) {
    return PR_FALSE;
  }

  PRBool supported;
  nsresult rv = loader->SupportImageWithMimeType(aMimeType.get(), &supported);
  return NS_SUCCEEDED(rv) && supported;
}

static PRBool
IsSupportedPlugin(const nsCString& aMIMEType)
{
  nsCOMPtr<nsIPluginHost> pluginHostCOM(do_GetService(MOZ_PLUGIN_HOST_CONTRACTID));
  nsPluginHost *pluginHost = static_cast<nsPluginHost*>(pluginHostCOM.get());
  if (!pluginHost) {
    return PR_FALSE;
  }
  nsresult rv = pluginHost->IsPluginEnabledForType(aMIMEType.get());
  return NS_SUCCEEDED(rv);
}

static void
GetExtensionFromURI(nsIURI* uri, nsCString& ext)
{
  nsCOMPtr<nsIURL> url(do_QueryInterface(uri));
  if (url) {
    url->GetFileExtension(ext);
  } else {
    nsCString spec;
    uri->GetSpec(spec);

    PRInt32 offset = spec.RFindChar('.');
    if (offset != kNotFound) {
      ext = Substring(spec, offset + 1, spec.Length());
    }
  }
}

/**
 * Checks whether a plugin exists and is enabled for the extension
 * in the given URI. The MIME type is returned in the mimeType out parameter.
 */
static PRBool
IsPluginEnabledByExtension(nsIURI* uri, nsCString& mimeType)
{
  nsCAutoString ext;
  GetExtensionFromURI(uri, ext);

  if (ext.IsEmpty()) {
    return PR_FALSE;
  }

  nsCOMPtr<nsIPluginHost> pluginHostCOM(do_GetService(MOZ_PLUGIN_HOST_CONTRACTID));
  nsPluginHost *pluginHost = static_cast<nsPluginHost*>(pluginHostCOM.get());
  if (!pluginHost) {
    return PR_FALSE;
  }

  const char* typeFromExt;
  if (NS_SUCCEEDED(pluginHost->IsPluginEnabledForExtension(ext.get(), typeFromExt))) {
    mimeType = typeFromExt;
    return PR_TRUE;
  }
  return PR_FALSE;
}

nsObjectLoadingContent::nsObjectLoadingContent()
  : mPendingInstantiateEvent(nsnull)
  , mChannel(nsnull)
  , mType(eType_Loading)
  , mInstantiating(PR_FALSE)
  , mUserDisabled(PR_FALSE)
  , mSuppressed(PR_FALSE)
  , mNetworkCreated(PR_TRUE)
  , mFallbackReason(ePluginOtherState)
{
}

nsObjectLoadingContent::~nsObjectLoadingContent()
{
  DestroyImageLoadingContent();
  if (mFrameLoader) {
    mFrameLoader->Destroy();
  }
}

// nsIRequestObserver
NS_IMETHODIMP
nsObjectLoadingContent::OnStartRequest(nsIRequest *aRequest,
                                       nsISupports *aContext)
{
  if (aRequest != mChannel) {
    // This is a bit of an edge case - happens when a new load starts before the
    // previous one got here
    return NS_BINDING_ABORTED;
  }

  AutoNotifier notifier(this, PR_TRUE);

  if (!IsSuccessfulRequest(aRequest)) {
    LOG(("OBJLC [%p]: OnStartRequest: Request failed\n", this));
    Fallback(PR_FALSE);
    return NS_BINDING_ABORTED;
  }

  nsCOMPtr<nsIChannel> chan(do_QueryInterface(aRequest));
  NS_ASSERTION(chan, "Why is our request not a channel?");

  nsresult rv = NS_ERROR_UNEXPECTED;
  // This fallback variable MUST be declared after the notifier variable. Do NOT
  // change the order of the declarations!
  AutoFallback fallback(this, &rv);

  nsCString channelType;
  rv = chan->GetContentType(channelType);
  NS_ENSURE_SUCCESS(rv, rv);

  if (channelType.EqualsASCII(APPLICATION_GUESS_FROM_EXT)) {
    channelType = APPLICATION_OCTET_STREAM;
    chan->SetContentType(channelType);
  }

  // We want to use the channel type unless one of the following is
  // true:
  //
  // 1) The channel type is application/octet-stream and we have a
  //    type hint and the type hint is not a document type.
  // 2) Our type hint is a type that we support with a plugin.

  if ((channelType.EqualsASCII(APPLICATION_OCTET_STREAM) && 
       !mContentType.IsEmpty() &&
       GetTypeOfContent(mContentType) != eType_Document) ||
      // Need to check IsSupportedPlugin() in addition to GetTypeOfContent()
      // because otherwise the default plug-in's catch-all behavior would
      // confuse things.
      (IsSupportedPlugin(mContentType) && 
       GetTypeOfContent(mContentType) == eType_Plugin)) {
    // Set the type we'll use for dispatch on the channel.  Otherwise we could
    // end up trying to dispatch to a nsFrameLoader, which will complain that
    // it couldn't find a way to handle application/octet-stream

    nsCAutoString typeHint, dummy;
    NS_ParseContentType(mContentType, typeHint, dummy);
    if (!typeHint.IsEmpty()) {
      chan->SetContentType(typeHint);
    }
  } else {
    mContentType = channelType;
  }

  nsCOMPtr<nsIURI> uri;
  chan->GetURI(getter_AddRefs(uri));

  if (mContentType.EqualsASCII(APPLICATION_OCTET_STREAM)) {
    nsCAutoString extType;
    if (IsPluginEnabledByExtension(uri, extType)) {
      mContentType = extType;
      chan->SetContentType(extType);
    }
  }

  // Now find out what type the content is
  // UnloadContent will set our type to null; need to be sure to only set it to
  // the real value on success
  ObjectType newType = GetTypeOfContent(mContentType);
  LOG(("OBJLC [%p]: OnStartRequest: Content Type=<%s> Old type=%u New Type=%u\n",
       this, mContentType.get(), mType, newType));

  // Now do a content policy check
  // XXXbz this duplicates some code in nsContentBlocker::ShouldLoad  
  PRInt32 contentPolicyType;
  switch (newType) {
    case eType_Image:
      contentPolicyType = nsIContentPolicy::TYPE_IMAGE;
      break;
    case eType_Document:
      contentPolicyType = nsIContentPolicy::TYPE_SUBDOCUMENT;
      break;
    default:
      contentPolicyType = nsIContentPolicy::TYPE_OBJECT;
      break;
  }
  nsCOMPtr<nsIContent> thisContent = 
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  NS_ASSERTION(thisContent, "must be a content");

  nsIDocument* doc = thisContent->GetOwnerDoc();
  if (!doc) {
    Fallback(PR_FALSE);
    return NS_BINDING_ABORTED;    
  }

  PRInt16 shouldProcess = nsIContentPolicy::ACCEPT;
  rv =
    NS_CheckContentProcessPolicy(contentPolicyType,
                                 uri,
                                 doc->NodePrincipal(),
                                 static_cast<nsIImageLoadingContent*>(this),
                                 mContentType,
                                 nsnull, //extra
                                 &shouldProcess,
                                 nsContentUtils::GetContentPolicy(),
                                 nsContentUtils::GetSecurityManager());
  if (NS_FAILED(rv) || NS_CP_REJECTED(shouldProcess)) {
    HandleBeingBlockedByContentPolicy(rv, shouldProcess);
    rv = NS_OK; // otherwise, the AutoFallback will make us fall back
    return NS_BINDING_ABORTED;
  }  
  
  if (mType != newType) {
    UnloadContent();
  }

  switch (newType) {
    case eType_Image:
      rv = LoadImageWithChannel(chan, getter_AddRefs(mFinalListener));
      NS_ENSURE_SUCCESS(rv, rv);

      // If we have a success result but no final listener, then the image is
      // cached. In that case, we can just return: No need to try to call the
      // final listener.
      if (!mFinalListener) {
        mType = newType;
        return NS_BINDING_ABORTED;
      }
      break;
    case eType_Document: {
      if (!mFrameLoader) {
        mFrameLoader = nsFrameLoader::Create(thisContent, mNetworkCreated);
        if (!mFrameLoader) {
          Fallback(PR_FALSE);
          return NS_ERROR_UNEXPECTED;
        }
      }

      rv = mFrameLoader->CheckForRecursiveLoad(uri);
      if (NS_FAILED(rv)) {
        Fallback(PR_FALSE);
        return rv;
      }

      if (mType != newType) {
        // XXX We must call this before getting the docshell to work around
        // bug 300540; when that's fixed, this if statement can be removed.
        mType = newType;
        notifier.Notify();

        if (!mFrameLoader) {
          // mFrameLoader got nulled out when we notified, which most
          // likely means the node was removed from the
          // document. Abort the load that just started.
          return NS_BINDING_ABORTED;
        }
      }

      // We're loading a document, so we have to set LOAD_DOCUMENT_URI
      // (especially important for firing onload)
      nsLoadFlags flags = 0;
      chan->GetLoadFlags(&flags);
      flags |= nsIChannel::LOAD_DOCUMENT_URI;
      chan->SetLoadFlags(flags);

      nsCOMPtr<nsIDocShell> docShell;
      rv = mFrameLoader->GetDocShell(getter_AddRefs(docShell));
      NS_ENSURE_SUCCESS(rv, rv);

      nsCOMPtr<nsIInterfaceRequestor> req(do_QueryInterface(docShell));
      NS_ASSERTION(req, "Docshell must be an ifreq");

      nsCOMPtr<nsIURILoader>
        uriLoader(do_GetService(NS_URI_LOADER_CONTRACTID, &rv));
      NS_ENSURE_SUCCESS(rv, rv);
      rv = uriLoader->OpenChannel(chan, nsIURILoader::DONT_RETARGET, req,
                                  getter_AddRefs(mFinalListener));
      break;
    }
    case eType_Plugin:
      mInstantiating = PR_TRUE;
      if (mType != newType) {
        // This can go away once plugin loading moves to content (bug 90268)
        mType = newType;
        notifier.Notify();
      }
      nsIObjectFrame* frame;
      frame = GetExistingFrame(eFlushLayout);
      if (!frame) {
        // Do nothing in this case: This is probably due to a display:none
        // frame. If we ever get a frame, HasNewFrame will do the right thing.
        // Abort the load though, we have no use for the data.
        mInstantiating = PR_FALSE;
        return NS_BINDING_ABORTED;
      }

      {
        nsIFrame *nsiframe = do_QueryFrame(frame);

        nsWeakFrame weakFrame(nsiframe);

        rv = frame->Instantiate(chan, getter_AddRefs(mFinalListener));

        mInstantiating = PR_FALSE;

        if (!weakFrame.IsAlive()) {
          // The frame was destroyed while instantiating. Abort the load.
          return NS_BINDING_ABORTED;
        }
      }

      break;
    case eType_Loading:
      NS_NOTREACHED("Should not have a loading type here!");
    case eType_Null:
      LOG(("OBJLC [%p]: Unsupported type, falling back\n", this));
      // Need to fallback here (instead of using the case below), so that we can
      // set mFallbackReason without it being overwritten. This is also why we
      // return early.
      Fallback(PR_FALSE);

      PluginSupportState pluginState = GetPluginSupportState(thisContent,
                                                             mContentType);
      // Do nothing, but fire the plugin not found event if needed
      if (pluginState != ePluginOtherState) {
        mFallbackReason = pluginState;
        FirePluginError(thisContent, pluginState);
      }
      return NS_BINDING_ABORTED;
  }

  if (mFinalListener) {
    mType = newType;
    rv = mFinalListener->OnStartRequest(aRequest, aContext);
    if (NS_FAILED(rv)) {
      LOG(("OBJLC [%p]: mFinalListener->OnStartRequest failed (%08x), falling back\n",
           this, rv));
#ifdef XP_MACOSX
      // Shockwave on Mac is special and returns an error here even when it
      // handles the content
      if (mContentType.EqualsLiteral("application/x-director")) {
        LOG(("OBJLC [%p]: (ignoring)\n", this));
        rv = NS_OK; // otherwise, the AutoFallback will make us fall back
        return NS_BINDING_ABORTED;
      }
#endif
      Fallback(PR_FALSE);
    } else if (mType == eType_Plugin) {
      nsIObjectFrame* frame = GetExistingFrame(eFlushContent);
      if (frame) {
        // We have to notify the wrapper here instead of right after
        // Instantiate because the plugin only gets instantiated by
        // OnStartRequest, not by Instantiate.
        frame->TryNotifyContentObjectWrapper();
      }
    }
    return rv;
  }

  LOG(("OBJLC [%p]: Found no listener, falling back\n", this));
  Fallback(PR_FALSE);
  return NS_BINDING_ABORTED;
}

NS_IMETHODIMP
nsObjectLoadingContent::OnStopRequest(nsIRequest *aRequest,
                                      nsISupports *aContext,
                                      nsresult aStatusCode)
{
  if (aRequest != mChannel) {
    return NS_BINDING_ABORTED;
  }

  mChannel = nsnull;

  if (mFinalListener) {
    mFinalListener->OnStopRequest(aRequest, aContext, aStatusCode);
    mFinalListener = nsnull;
  }

  // Return value doesn't matter
  return NS_OK;
}


// nsIStreamListener
NS_IMETHODIMP
nsObjectLoadingContent::OnDataAvailable(nsIRequest *aRequest, nsISupports *aContext, nsIInputStream *aInputStream, PRUint32 aOffset, PRUint32 aCount)
{
  if (aRequest != mChannel) {
    return NS_BINDING_ABORTED;
  }

  if (mFinalListener) {
    return mFinalListener->OnDataAvailable(aRequest, aContext, aInputStream, aOffset, aCount);
  }

  // Abort this load if we have no listener here
  return NS_ERROR_UNEXPECTED;
}

// nsIFrameLoaderOwner
NS_IMETHODIMP
nsObjectLoadingContent::GetFrameLoader(nsIFrameLoader** aFrameLoader)
{
  *aFrameLoader = mFrameLoader;
  NS_IF_ADDREF(*aFrameLoader);
  return NS_OK;
}

NS_IMETHODIMP_(already_AddRefed<nsFrameLoader>)
nsObjectLoadingContent::GetFrameLoader()
{
  nsFrameLoader* loader = mFrameLoader;
  NS_IF_ADDREF(loader);
  return loader;
}

NS_IMETHODIMP
nsObjectLoadingContent::SwapFrameLoaders(nsIFrameLoaderOwner* aOtherLoader)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

// nsIObjectLoadingContent
NS_IMETHODIMP
nsObjectLoadingContent::GetActualType(nsACString& aType)
{
  aType = mContentType;
  return NS_OK;
}

NS_IMETHODIMP
nsObjectLoadingContent::GetDisplayedType(PRUint32* aType)
{
  *aType = mType;
  return NS_OK;
}


NS_IMETHODIMP
nsObjectLoadingContent::EnsureInstantiation(nsNPAPIPluginInstance** aInstance)
{
  // Must set our out parameter to null as we have various early returns with
  // an NS_OK result.
  *aInstance = nsnull;

  if (mType != eType_Plugin) {
    return NS_OK;
  }

  nsIObjectFrame* frame = GetExistingFrame(eFlushContent);
  if (frame) {
    // If we have a frame, we may have pending instantiate events; revoke
    // them.
    if (mPendingInstantiateEvent) {
      LOG(("OBJLC [%p]: Revoking pending instantiate event\n", this));
      mPendingInstantiateEvent = nsnull;
    }
  } else {
    // mInstantiating is true if we're in LoadObject; we shouldn't
    // recreate frames in that case, we'd confuse that function.
    if (mInstantiating) {
      return NS_OK;
    }

    // Trigger frame construction
    mInstantiating = PR_TRUE;

    nsCOMPtr<nsIContent> thisContent = 
      do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
    NS_ASSERTION(thisContent, "must be a content");

    nsIDocument* doc = thisContent->GetCurrentDoc();
    if (!doc) {
      // Nothing we can do while plugin loading is done in layout...
      mInstantiating = PR_FALSE;
      return NS_OK;
    }

    doc->FlushPendingNotifications(Flush_Frames);

    mInstantiating = PR_FALSE;

    frame = GetExistingFrame(eFlushContent);
    if (!frame) {
      return NS_OK;
    }
  }

  nsIFrame *nsiframe = do_QueryFrame(frame);

  if (nsiframe->GetStateBits() & NS_FRAME_FIRST_REFLOW) {
    // A frame for this plugin element already exists now, but it has
    // not been reflowed yet. Force a reflow now so that we don't end
    // up initializing a plugin before knowing its size. Also re-fetch
    // the frame, as flushing can cause the frame to be deleted.
    frame = GetExistingFrame(eFlushLayout);

    if (!frame) {
      return NS_OK;
    }

    nsiframe = do_QueryFrame(frame);
  }

  nsWeakFrame weakFrame(nsiframe);

  // We may have a plugin instance already; if so, do nothing
  nsresult rv = frame->GetPluginInstance(aInstance);
  if (!*aInstance && weakFrame.IsAlive()) {
    rv = Instantiate(frame, mContentType, mURI);
    if (NS_SUCCEEDED(rv) && weakFrame.IsAlive()) {
      rv = frame->GetPluginInstance(aInstance);
    } else {
      Fallback(PR_TRUE);
    }
  }
  return rv;
}

NS_IMETHODIMP
nsObjectLoadingContent::HasNewFrame(nsIObjectFrame* aFrame)
{
  LOG(("OBJLC [%p]: Got frame %p (mInstantiating=%i)\n", this, aFrame,
       mInstantiating));

  nsCOMPtr<nsIContent> thisContent = 
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  NS_ASSERTION(thisContent, "must be a content");
  nsIDocument* doc = thisContent->GetOwnerDoc();
  if (!doc || doc->IsStaticDocument() || doc->IsBeingUsedAsImage()) {
    return NS_OK;
  }

  // "revoke" any existing instantiate event as it likely has out of
  // date data (frame pointer etc).
  mPendingInstantiateEvent = nsnull;

  nsRefPtr<nsNPAPIPluginInstance> instance;
  aFrame->GetPluginInstance(getter_AddRefs(instance));

  if (instance) {
    // The frame already has a plugin instance, that means the plugin
    // has already been instantiated.

    return NS_OK;
  }

  if (!mInstantiating && mType == eType_Plugin) {
    // Asynchronously call Instantiate
    // This can go away once plugin loading moves to content
    // This must be done asynchronously to ensure that the frame is correctly
    // initialized (has a view etc)

    // When in a plugin document, the document will take care of calling
    // instantiate
    nsCOMPtr<nsIPluginDocument> pDoc (do_QueryInterface(GetOurDocument()));
    if (pDoc) {
      PRBool willHandleInstantiation;
      pDoc->GetWillHandleInstantiation(&willHandleInstantiation);
      if (willHandleInstantiation) {
        return NS_OK;
      }
    }

    nsIFrame* frame = do_QueryFrame(aFrame);
    nsCOMPtr<nsIRunnable> event =
      new nsAsyncInstantiateEvent(this, frame, mContentType, mURI);
    if (!event) {
      return NS_ERROR_OUT_OF_MEMORY;
    }

    LOG(("                 dispatching event\n"));
    nsresult rv = NS_DispatchToCurrentThread(event);
    if (NS_FAILED(rv)) {
      NS_ERROR("failed to dispatch nsAsyncInstantiateEvent");
    } else {
      // Remember this event.  This is a weak reference that will be cleared
      // when the event runs.
      mPendingInstantiateEvent = event;
    }
  }
  return NS_OK;
}

NS_IMETHODIMP
nsObjectLoadingContent::GetPluginInstance(nsNPAPIPluginInstance** aInstance)
{
  *aInstance = nsnull;

  nsIObjectFrame* objFrame = GetExistingFrame(eDontFlush);
  if (!objFrame) {
    return NS_OK;
  }

  return objFrame->GetPluginInstance(aInstance);
}

NS_IMETHODIMP
nsObjectLoadingContent::GetContentTypeForMIMEType(const nsACString& aMIMEType,
                                                  PRUint32* aType)
{
  *aType = GetTypeOfContent(PromiseFlatCString(aMIMEType));
  return NS_OK;
}

// nsIInterfaceRequestor
NS_IMETHODIMP
nsObjectLoadingContent::GetInterface(const nsIID & aIID, void **aResult)
{
  if (aIID.Equals(NS_GET_IID(nsIChannelEventSink))) {
    nsIChannelEventSink* sink = this;
    *aResult = sink;
    NS_ADDREF(sink);
    return NS_OK;
  }
  return NS_NOINTERFACE;
}

// nsIChannelEventSink
NS_IMETHODIMP
nsObjectLoadingContent::AsyncOnChannelRedirect(nsIChannel *aOldChannel,
                                               nsIChannel *aNewChannel,
                                               PRUint32 aFlags,
                                               nsIAsyncVerifyRedirectCallback *cb)
{
  // If we're already busy with a new load, or have no load at all,
  // cancel the redirect.
  if (!mChannel || aOldChannel != mChannel) {
    return NS_BINDING_ABORTED;
  }

  mChannel = aNewChannel;
  cb->OnRedirectVerifyCallback(NS_OK);
  return NS_OK;
}

// <public>
nsEventStates
nsObjectLoadingContent::ObjectState() const
{
  switch (mType) {
    case eType_Loading:
      return NS_EVENT_STATE_LOADING;
    case eType_Image:
      return ImageState();
    case eType_Plugin:
    case eType_Document:
      // These are OK. If documents start to load successfully, they display
      // something, and are thus not broken in this sense. The same goes for
      // plugins.
      return nsEventStates();
    case eType_Null:
      if (mSuppressed)
        return NS_EVENT_STATE_SUPPRESSED;
      if (mUserDisabled)
        return NS_EVENT_STATE_USERDISABLED;

      // Otherwise, broken
      nsEventStates state = NS_EVENT_STATE_BROKEN;
      switch (mFallbackReason) {
        case ePluginDisabled:
          state |= NS_EVENT_STATE_HANDLER_DISABLED;
          break;
        case ePluginBlocklisted:
          state |= NS_EVENT_STATE_HANDLER_BLOCKED;
          break;
        case ePluginCrashed:
          state |= NS_EVENT_STATE_HANDLER_CRASHED;
          break;
        case ePluginUnsupported:
          state |= NS_EVENT_STATE_TYPE_UNSUPPORTED;
          break;
        case ePluginOutdated:
        case ePluginOtherState:
          // Do nothing, but avoid a compile warning
          break;
      }
      return state;
  };
  NS_NOTREACHED("unknown type?");
  // this return statement only exists to avoid a compile warning
  return nsEventStates();
}

// <protected>
nsresult
nsObjectLoadingContent::LoadObject(const nsAString& aURI,
                                   PRBool aNotify,
                                   const nsCString& aTypeHint,
                                   PRBool aForceLoad)
{
  LOG(("OBJLC [%p]: Loading object: URI string=<%s> notify=%i type=<%s> forceload=%i\n",
       this, NS_ConvertUTF16toUTF8(aURI).get(), aNotify, aTypeHint.get(), aForceLoad));

  NS_ASSERTION(!mInstantiating, "LoadObject was reentered?");

  // Avoid StringToURI in order to use the codebase attribute as base URI
  nsCOMPtr<nsIContent> thisContent = 
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  NS_ASSERTION(thisContent, "must be a content");

  nsIDocument* doc = thisContent->GetOwnerDoc();
  nsCOMPtr<nsIURI> baseURI;
  GetObjectBaseURI(thisContent, getter_AddRefs(baseURI));

  nsCOMPtr<nsIURI> uri;
  nsContentUtils::NewURIWithDocumentCharset(getter_AddRefs(uri),
                                            aURI, doc,
                                            baseURI);
  // If URI creation failed, fallback immediately - this only happens for
  // malformed URIs
  if (!uri) {
    Fallback(aNotify);
    return NS_OK;
  }

  NS_TryToSetImmutable(uri);

  return LoadObject(uri, aNotify, aTypeHint, aForceLoad);
}

static PRBool
IsAboutBlank(nsIURI* aURI)
{
  // XXXbz this duplicates an nsDocShell function, sadly
  NS_PRECONDITION(aURI, "Must have URI");
    
  // GetSpec can be expensive for some URIs, so check the scheme first.
  PRBool isAbout = PR_FALSE;
  if (NS_FAILED(aURI->SchemeIs("about", &isAbout)) || !isAbout) {
    return PR_FALSE;
  }
    
  nsCAutoString str;
  aURI->GetSpec(str);
  return str.EqualsLiteral("about:blank");  
}

void
nsObjectLoadingContent::UpdateFallbackState(nsIContent* aContent,
                                            AutoFallback& fallback,
                                            const nsCString& aTypeHint)
{
  // Notify the UI and update the fallback state
  PluginSupportState state = GetPluginSupportState(aContent, aTypeHint);
  if (state != ePluginOtherState) {
    fallback.SetPluginState(state);
    FirePluginError(aContent, state);
  }
}

nsresult
nsObjectLoadingContent::LoadObject(nsIURI* aURI,
                                   PRBool aNotify,
                                   const nsCString& aTypeHint,
                                   PRBool aForceLoad)
{
  LOG(("OBJLC [%p]: Loading object: URI=<%p> notify=%i type=<%s> forceload=%i\n",
       this, aURI, aNotify, aTypeHint.get(), aForceLoad));

  if (mURI && aURI && !aForceLoad) {
    PRBool equal;
    nsresult rv = mURI->Equals(aURI, &equal);
    if (NS_SUCCEEDED(rv) && equal) {
      // URI didn't change, do nothing
      return NS_OK;
    }
  }

  // Need to revoke any potentially pending instantiate events
  if (mType == eType_Plugin && mPendingInstantiateEvent) {
    LOG(("OBJLC [%p]: Revoking pending instantiate event\n", this));
    mPendingInstantiateEvent = nsnull;
  }

  AutoNotifier notifier(this, aNotify);

  // AutoSetInstantiatingToFalse is instantiated after AutoNotifier, so that if
  // the AutoNotifier triggers frame construction, events can be posted as
  // appropriate.
  NS_ASSERTION(!mInstantiating, "LoadObject was reentered?");
  mInstantiating = PR_TRUE;
  AutoSetInstantiatingToFalse autoset(this);

  mUserDisabled = mSuppressed = PR_FALSE;

  mURI = aURI;
  mContentType = aTypeHint;

  nsCOMPtr<nsIContent> thisContent = 
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  NS_ASSERTION(thisContent, "must be a content");

  nsIDocument* doc = thisContent->GetOwnerDoc();
  if (!doc || doc->IsBeingUsedAsImage()) {
    return NS_OK;
  }

  // From here on, we will always change the content. This means that a
  // possibly-loading channel should be aborted.
  if (mChannel) {
    LOG(("OBJLC [%p]: Cancelling existing load\n", this));

    // These three statements are carefully ordered:
    // - onStopRequest should get a channel whose status is the same as the
    //   status argument
    // - onStopRequest must get a non-null channel
    mChannel->Cancel(NS_BINDING_ABORTED);
    if (mFinalListener) {
      // NOTE: Since mFinalListener is only set in onStartRequest, which takes
      // care of calling mFinalListener->OnStartRequest, mFinalListener is only
      // non-null here if onStartRequest was already called.
      mFinalListener->OnStopRequest(mChannel, nsnull, NS_BINDING_ABORTED);
      mFinalListener = nsnull;
    }
    mChannel = nsnull;
  }

  // Security checks
  if (doc->IsLoadedAsData()) {
    if (!doc->IsStaticDocument()) {
      Fallback(PR_FALSE);
    }
    return NS_OK;
  }

  // Can't do security checks without a URI - hopefully the plugin will take
  // care of that
  // Null URIs happen when the URL to load is specified via other means than the
  // data/src attribute, for example via custom <param> elements.
  if (aURI) {
    nsIScriptSecurityManager* secMan = nsContentUtils::GetSecurityManager();
    NS_ASSERTION(secMan, "No security manager!?");
    nsresult rv =
      secMan->CheckLoadURIWithPrincipal(thisContent->NodePrincipal(), aURI, 0);
    if (NS_FAILED(rv)) {
      Fallback(PR_FALSE);
      return NS_OK;
    }

    PRInt16 shouldLoad = nsIContentPolicy::ACCEPT; // default permit
    rv =
      NS_CheckContentLoadPolicy(nsIContentPolicy::TYPE_OBJECT,
                                aURI,
                                doc->NodePrincipal(),
                                static_cast<nsIImageLoadingContent*>(this),
                                aTypeHint,
                                nsnull, //extra
                                &shouldLoad,
                                nsContentUtils::GetContentPolicy(),
                                secMan);
    if (NS_FAILED(rv) || NS_CP_REJECTED(shouldLoad)) {
      HandleBeingBlockedByContentPolicy(rv, shouldLoad);
      return NS_OK;
    }
  }

  nsresult rv = NS_ERROR_UNEXPECTED;
  // This fallback variable MUST be declared after the notifier variable. Do NOT
  // change the order of the declarations!
  AutoFallback fallback(this, &rv);

  PRUint32 caps = GetCapabilities();
  LOG(("OBJLC [%p]: Capabilities: %04x\n", this, caps));

  nsCAutoString overrideType;
  if ((caps & eOverrideServerType) &&
      ((!aTypeHint.IsEmpty() && IsSupportedPlugin(aTypeHint)) ||
       (aURI && IsPluginEnabledByExtension(aURI, overrideType)))) {
    ObjectType newType;
    if (overrideType.IsEmpty()) {
      newType = GetTypeOfContent(aTypeHint);
    } else {
      mContentType = overrideType;
      newType = eType_Plugin;
    }

    if (newType != mType) {
      LOG(("OBJLC [%p]: (eOverrideServerType) Changing type from %u to %u\n", this, mType, newType));

      UnloadContent();

      // Must have a frameloader before creating a frame, or the frame will
      // create its own.
      if (!mFrameLoader && newType == eType_Document) {
        mFrameLoader = nsFrameLoader::Create(thisContent, mNetworkCreated);
        if (!mFrameLoader) {
          mURI = nsnull;
          return NS_OK;
        }
      }

      // Must notify here for plugins
      // If aNotify is false, we'll just wait until we get a frame and use the
      // async instantiate path.
      // XXX is this still needed? (for documents?)
      mType = newType;
      if (aNotify)
        notifier.Notify();
    }
    switch (newType) {
      case eType_Image:
        // Don't notify, because we will take care of that ourselves.
        if (aURI) {
          rv = LoadImage(aURI, aForceLoad, PR_FALSE);
        } else {
          rv = NS_ERROR_NOT_AVAILABLE;
        }
        break;
      case eType_Plugin:
        rv = TryInstantiate(mContentType, mURI);
        break;
      case eType_Document:
        if (aURI) {
          rv = mFrameLoader->LoadURI(aURI);
        } else {
          rv = NS_ERROR_NOT_AVAILABLE;
        }
        break;
      case eType_Loading:
        NS_NOTREACHED("Should not have a loading type here!");
      case eType_Null:
        // No need to load anything, notify of the failure.
        UpdateFallbackState(thisContent, fallback, aTypeHint);
        break;
    };
    return NS_OK;
  }

  // If the class ID specifies a supported plugin, or if we have no explicit URI
  // but a type, immediately instantiate the plugin.
  PRBool isSupportedClassID = PR_FALSE;
  nsCAutoString typeForID; // Will be set iff isSupportedClassID == PR_TRUE
  PRBool hasID = PR_FALSE;
  if (caps & eSupportClassID) {
    nsAutoString classid;
    thisContent->GetAttr(kNameSpaceID_None, nsGkAtoms::classid, classid);
    if (!classid.IsEmpty()) {
      hasID = PR_TRUE;
      isSupportedClassID = NS_SUCCEEDED(TypeForClassID(classid, typeForID));
    }
  }

  if (hasID && !isSupportedClassID) {
    // We have a class ID and it's unsupported.  Fallback in that case.
    LOG(("OBJLC [%p]: invalid classid\n", this));
    rv = NS_ERROR_NOT_AVAILABLE;
    return NS_OK;
  }

  if (isSupportedClassID ||
      (!aURI && !aTypeHint.IsEmpty() &&
       GetTypeOfContent(aTypeHint) == eType_Plugin)) {
    // No URI, but we have a type. The plugin will handle the load.
    // Or: supported class id, plugin will handle the load.
    LOG(("OBJLC [%p]: (classid) Changing type from %u to eType_Plugin\n", this, mType));
    mType = eType_Plugin;

    // At this point, the stored content type
    // must be equal to our type hint. Similar,
    // our URI must be the requested URI.
    // (->Equals would suffice, but == is cheaper
    // and handles NULL)
    NS_ASSERTION(mContentType.Equals(aTypeHint), "mContentType wrong!");
    NS_ASSERTION(mURI == aURI, "mURI wrong!");

    if (isSupportedClassID) {
      // Use the classid's type
      NS_ASSERTION(!typeForID.IsEmpty(), "Must have a real type!");
      mContentType = typeForID;
      // XXX(biesi). The plugin instantiation code used to pass the base URI
      // here instead of the plugin URI for instantiation via class ID, so I
      // continue to do so. Why that is, no idea...
      GetObjectBaseURI(thisContent, getter_AddRefs(mURI));
      if (!mURI) {
        mURI = aURI;
      }
    }

    rv = TryInstantiate(mContentType, mURI);
    return NS_OK;
  }

  if (!aURI) {
    // No URI and if we have got this far no enabled plugin supports the type
    LOG(("OBJLC [%p]: no URI\n", this));
    rv = NS_ERROR_NOT_AVAILABLE;

    // We should only notify the UI if there is at least a type to go on for
    // finding a plugin to use, unless it's a supported image or document type.
    if (!aTypeHint.IsEmpty() && GetTypeOfContent(aTypeHint) == eType_Null) {
      UpdateFallbackState(thisContent, fallback, aTypeHint);
    }

    return NS_OK;
  }

  // E.g. mms://
  if (!CanHandleURI(aURI)) {
    LOG(("OBJLC [%p]: can't handle URI\n", this));
    if (aTypeHint.IsEmpty()) {
      rv = NS_ERROR_NOT_AVAILABLE;
      return NS_OK;
    }

    if (IsSupportedPlugin(aTypeHint)) {
      mType = eType_Plugin;

      rv = TryInstantiate(aTypeHint, aURI);
    } else {
      rv = NS_ERROR_NOT_AVAILABLE;
      // No plugin to load, notify of the failure.
      UpdateFallbackState(thisContent, fallback, aTypeHint);
    }

    return NS_OK;
  }

  nsCOMPtr<nsILoadGroup> group = doc->GetDocumentLoadGroup();
  nsCOMPtr<nsIChannel> chan;
  nsCOMPtr<nsIChannelPolicy> channelPolicy;
  nsCOMPtr<nsIContentSecurityPolicy> csp;
  rv = doc->NodePrincipal()->GetCsp(getter_AddRefs(csp));
  NS_ENSURE_SUCCESS(rv, rv);
  if (csp) {
    channelPolicy = do_CreateInstance("@mozilla.org/nschannelpolicy;1");
    channelPolicy->SetContentSecurityPolicy(csp);
    channelPolicy->SetLoadType(nsIContentPolicy::TYPE_OBJECT);
  }
  rv = NS_NewChannel(getter_AddRefs(chan), aURI, nsnull, group, this,
                     nsIChannel::LOAD_CALL_CONTENT_SNIFFERS |
                     nsIChannel::LOAD_CLASSIFY_URI,
                     channelPolicy);
  NS_ENSURE_SUCCESS(rv, rv);

  // Referrer
  nsCOMPtr<nsIHttpChannel> httpChan(do_QueryInterface(chan));
  if (httpChan) {
    httpChan->SetReferrer(doc->GetDocumentURI());
  }

  // MIME Type hint
  if (!aTypeHint.IsEmpty()) {
    nsCAutoString typeHint, dummy;
    NS_ParseContentType(aTypeHint, typeHint, dummy);
    if (!typeHint.IsEmpty()) {
      chan->SetContentType(typeHint);
    }
  }

  // Set up the channel's principal and such, like nsDocShell::DoURILoad does
  PRBool inheritPrincipal;
  rv = NS_URIChainHasFlags(aURI,
                           nsIProtocolHandler::URI_INHERITS_SECURITY_CONTEXT,
                           &inheritPrincipal);
  NS_ENSURE_SUCCESS(rv, rv);
  if (inheritPrincipal || IsAboutBlank(aURI) ||
      (nsContentUtils::URIIsLocalFile(aURI) &&
       NS_SUCCEEDED(thisContent->NodePrincipal()->CheckMayLoad(aURI,
                                                               PR_FALSE)))) {
    chan->SetOwner(thisContent->NodePrincipal());
  }

  nsCOMPtr<nsIScriptChannel> scriptChannel = do_QueryInterface(chan);
  if (scriptChannel) {
    // Allow execution against our context if the principals match
    scriptChannel->
      SetExecutionPolicy(nsIScriptChannel::EXECUTE_NORMAL);
  }

  // AsyncOpen can fail if a file does not exist.
  // Show fallback content in that case.
  rv = chan->AsyncOpen(this, nsnull);
  if (NS_SUCCEEDED(rv)) {
    LOG(("OBJLC [%p]: Channel opened.\n", this));

    mChannel = chan;
    mType = eType_Loading;
  }
  return NS_OK;
}

PRUint32
nsObjectLoadingContent::GetCapabilities() const
{
  return eSupportImages |
         eSupportPlugins |
         eSupportDocuments |
         eSupportSVG;
}

void
nsObjectLoadingContent::Fallback(PRBool aNotify)
{
  LOG(("OBJLC [%p]: Falling back (Notify=%i)\n", this, aNotify));

  AutoNotifier notifier(this, aNotify);

  UnloadContent();
}

void
nsObjectLoadingContent::RemovedFromDocument()
{
  LOG(("OBJLC [%p]: Removed from doc\n", this));
  if (mFrameLoader) {
    // XXX This is very temporary and must go away
    mFrameLoader->Destroy();
    mFrameLoader = nsnull;

    // Clear the current URI, so that LoadObject doesn't think that we
    // have already loaded the content.
    mURI = nsnull;
  }
}

void
nsObjectLoadingContent::Traverse(nsCycleCollectionTraversalCallback &cb)
{
  cb.NoteXPCOMChild(static_cast<nsIFrameLoader*>(mFrameLoader));
}

// <private>
/* static */ PRBool
nsObjectLoadingContent::IsSuccessfulRequest(nsIRequest* aRequest)
{
  nsresult status;
  nsresult rv = aRequest->GetStatus(&status);
  if (NS_FAILED(rv) || NS_FAILED(status)) {
    return PR_FALSE;
  }

  // This may still be an error page or somesuch
  nsCOMPtr<nsIHttpChannel> httpChan(do_QueryInterface(aRequest));
  if (httpChan) {
    PRBool success;
    rv = httpChan->GetRequestSucceeded(&success);
    if (NS_FAILED(rv) || !success) {
      return PR_FALSE;
    }
  }

  // Otherwise, the request is successful
  return PR_TRUE;
}

/* static */ PRBool
nsObjectLoadingContent::CanHandleURI(nsIURI* aURI)
{
  nsCAutoString scheme;
  if (NS_FAILED(aURI->GetScheme(scheme))) {
    return PR_FALSE;
  }

  nsIIOService* ios = nsContentUtils::GetIOService();
  if (!ios)
    return PR_FALSE;
  
  nsCOMPtr<nsIProtocolHandler> handler;
  ios->GetProtocolHandler(scheme.get(), getter_AddRefs(handler));
  if (!handler) {
    return PR_FALSE;
  }
  
  nsCOMPtr<nsIExternalProtocolHandler> extHandler =
    do_QueryInterface(handler);
  // We can handle this URI if its protocol handler is not the external one
  return extHandler == nsnull;
}

PRBool
nsObjectLoadingContent::IsSupportedDocument(const nsCString& aMimeType)
{
  nsCOMPtr<nsIContent> thisContent = 
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  NS_ASSERTION(thisContent, "must be a content");

  nsresult rv;
  nsCOMPtr<nsIWebNavigationInfo> info(
    do_GetService(NS_WEBNAVIGATION_INFO_CONTRACTID, &rv));
  PRUint32 supported;
  if (info) {
    nsCOMPtr<nsIWebNavigation> webNav;
    nsIDocument* currentDoc = thisContent->GetCurrentDoc();
    if (currentDoc) {
      webNav = do_GetInterface(currentDoc->GetScriptGlobalObject());
    }
    rv = info->IsTypeSupported(aMimeType, webNav, &supported);
  }

  if (NS_SUCCEEDED(rv)) {
    if (supported == nsIWebNavigationInfo::UNSUPPORTED) {
      // Try a stream converter
      // NOTE: We treat any type we can convert from as a supported type. If a
      // type is not actually supported, the URI loader will detect that and
      // return an error, and we'll fallback.
      nsCOMPtr<nsIStreamConverterService> convServ =
        do_GetService("@mozilla.org/streamConverters;1");
      PRBool canConvert = PR_FALSE;
      if (convServ) {
        rv = convServ->CanConvert(aMimeType.get(), "*/*", &canConvert);
      }

      return NS_SUCCEEDED(rv) && canConvert;
    }

    // Don't want to support plugins as documents
    return supported != nsIWebNavigationInfo::PLUGIN;
  }

  return PR_FALSE;
}

void
nsObjectLoadingContent::UnloadContent()
{
  // Don't notify in CancelImageRequests. We do it ourselves.
  CancelImageRequests(PR_FALSE);
  if (mFrameLoader) {
    mFrameLoader->Destroy();
    mFrameLoader = nsnull;
  }
  mType = eType_Null;
  mUserDisabled = mSuppressed = PR_FALSE;
  mFallbackReason = ePluginOtherState;
}

void
nsObjectLoadingContent::NotifyStateChanged(ObjectType aOldType,
                                          nsEventStates aOldState, PRBool aSync)
{
  LOG(("OBJLC [%p]: Notifying about state change: (%u, %llx) -> (%u, %llx) (sync=%i)\n",
       this, aOldType, aOldState.GetInternalValue(), mType,
       ObjectState().GetInternalValue(), aSync));

  nsCOMPtr<nsIContent> thisContent = 
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  NS_ASSERTION(thisContent, "must be a content");

  nsIDocument* doc = thisContent->GetCurrentDoc();
  if (!doc) {
    return; // Nothing to do
  }

  nsEventStates newState = ObjectState();

  if (newState != aOldState) {
    // This will trigger frame construction
    NS_ASSERTION(thisContent->IsInDoc(), "Something is confused");
    nsEventStates changedBits = aOldState ^ newState;

    {
      nsAutoScriptBlocker scriptBlocker;
      doc->ContentStateChanged(thisContent, changedBits);
    }
    if (aSync) {
      // Make sure that frames are actually constructed, and do it after
      // EndUpdate was called.
      doc->FlushPendingNotifications(Flush_Frames);
    }
  } else if (aOldType != mType) {
    // If our state changed, then we already recreated frames
    // Otherwise, need to do that here
    nsCOMPtr<nsIPresShell> shell = doc->GetShell();
    if (shell) {
      shell->RecreateFramesFor(thisContent);
    }
  }
}

/* static */ void
nsObjectLoadingContent::FirePluginError(nsIContent* thisContent,
                                        PluginSupportState state)
{
  LOG(("OBJLC []: Dispatching nsPluginErrorEvent for content %p\n",
       thisContent));

  nsCOMPtr<nsIRunnable> ev = new nsPluginErrorEvent(thisContent, state);
  nsresult rv = NS_DispatchToCurrentThread(ev);
  if (NS_FAILED(rv)) {
    NS_WARNING("failed to dispatch nsPluginErrorEvent");
  }
}

nsObjectLoadingContent::ObjectType
nsObjectLoadingContent::GetTypeOfContent(const nsCString& aMIMEType)
{
  PRUint32 caps = GetCapabilities();

  if ((caps & eSupportImages) && IsSupportedImage(aMIMEType)) {
    return eType_Image;
  }

  PRBool isSVG = aMIMEType.LowerCaseEqualsLiteral("image/svg+xml");
  PRBool supportedSVG = isSVG && (caps & eSupportSVG);
  if (((caps & eSupportDocuments) || supportedSVG) &&
      IsSupportedDocument(aMIMEType)) {
    return eType_Document;
  }

  if ((caps & eSupportPlugins) && IsSupportedPlugin(aMIMEType)) {
    return eType_Plugin;
  }

  return eType_Null;
}

nsresult
nsObjectLoadingContent::TypeForClassID(const nsAString& aClassID,
                                       nsACString& aType)
{
  nsCOMPtr<nsIPluginHost> pluginHostCOM(do_GetService(MOZ_PLUGIN_HOST_CONTRACTID));
  nsPluginHost *pluginHost = static_cast<nsPluginHost*>(pluginHostCOM.get());
  if (!pluginHost) {
    return NS_ERROR_NOT_AVAILABLE;
  }

  if (StringBeginsWith(aClassID, NS_LITERAL_STRING("java:"))) {
    // Supported if we have a java plugin
    aType.AssignLiteral("application/x-java-vm");
    nsresult rv = pluginHost->IsPluginEnabledForType("application/x-java-vm");
    return NS_SUCCEEDED(rv) ? NS_OK : NS_ERROR_NOT_AVAILABLE;
  }

  // If it starts with "clsid:", this is ActiveX content
  if (StringBeginsWith(aClassID, NS_LITERAL_STRING("clsid:"), nsCaseInsensitiveStringComparator())) {
    // Check if we have a plugin for that

    if (NS_SUCCEEDED(pluginHost->IsPluginEnabledForType("application/x-oleobject"))) {
      aType.AssignLiteral("application/x-oleobject");
      return NS_OK;
    }
    if (NS_SUCCEEDED(pluginHost->IsPluginEnabledForType("application/oleobject"))) {
      aType.AssignLiteral("application/oleobject");
      return NS_OK;
    }
  }

  return NS_ERROR_NOT_AVAILABLE;
}

void
nsObjectLoadingContent::GetObjectBaseURI(nsIContent* thisContent, nsIURI** aURI)
{
  // We want to use swap(); since this is just called from this file,
  // we can assert this (callers use comptrs)
  NS_PRECONDITION(*aURI == nsnull, "URI must be inited to zero");

  // For plugins, the codebase attribute is the base URI
  nsCOMPtr<nsIURI> baseURI = thisContent->GetBaseURI();
  nsAutoString codebase;
  thisContent->GetAttr(kNameSpaceID_None, nsGkAtoms::codebase,
                       codebase);
  if (!codebase.IsEmpty()) {
    nsContentUtils::NewURIWithDocumentCharset(aURI, codebase,
                                              thisContent->GetOwnerDoc(),
                                              baseURI);
  } else {
    baseURI.swap(*aURI);
  }
}

nsIObjectFrame*
nsObjectLoadingContent::GetExistingFrame(FlushType aFlushType)
{
  nsCOMPtr<nsIContent> thisContent = 
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  NS_ASSERTION(thisContent, "must be a content");

  nsIFrame* frame;
  do {
    frame = thisContent->GetPrimaryFrame();
    if (!frame) {
      return nsnull;
    }

    if (aFlushType == eDontFlush) {
      break;
    }
    
    // OK, let's flush out and try again.  Note that we want to reget
    // the document, etc, since flushing might run script.
    nsIDocument* doc = thisContent->GetCurrentDoc();
    NS_ASSERTION(doc, "Frame but no document?");
    mozFlushType flushType =
      aFlushType == eFlushLayout ? Flush_Layout : Flush_ContentAndNotify;
    doc->FlushPendingNotifications(flushType);

    aFlushType = eDontFlush;
  } while (1);

  nsIObjectFrame* objFrame = do_QueryFrame(frame);
  return objFrame;
}

void
nsObjectLoadingContent::HandleBeingBlockedByContentPolicy(nsresult aStatus,
                                                          PRInt16 aRetval)
{
  // Must call UnloadContent first, as it overwrites
  // mSuppressed/mUserDisabled. It also takes care of setting the type to
  // eType_Null.
  UnloadContent();
  if (NS_SUCCEEDED(aStatus)) {
    if (aRetval == nsIContentPolicy::REJECT_TYPE) {
      mUserDisabled = PR_TRUE;
    } else if (aRetval == nsIContentPolicy::REJECT_SERVER) {
      mSuppressed = PR_TRUE;
    }
  }
}

nsresult
nsObjectLoadingContent::TryInstantiate(const nsACString& aMIMEType,
                                       nsIURI* aURI)
{
  nsIObjectFrame* frame = GetExistingFrame(eFlushContent);
  if (!frame) {
    LOG(("OBJLC [%p]: No frame yet\n", this));
    return NS_OK; // Not a failure to have no frame
  }

  nsRefPtr<nsNPAPIPluginInstance> instance;
  frame->GetPluginInstance(getter_AddRefs(instance));

  if (!instance) {
    // The frame has no plugin instance yet. If the frame hasn't been
    // reflowed yet, do nothing as once the reflow happens we'll end up
    // instantiating the plugin with the correct size n' all (which
    // isn't known until we've done the first reflow). But if the
    // frame does have a plugin instance already, be sure to
    // re-instantiate the plugin as its source or whatnot might have
    // chanced since it was instantiated.
    nsIFrame* iframe = do_QueryFrame(frame);
    if (iframe->GetStateBits() & NS_FRAME_FIRST_REFLOW) {
      LOG(("OBJLC [%p]: Frame hasn't been reflowed yet\n", this));
      return NS_OK; // Not a failure to have no frame
    }
  }

  return Instantiate(frame, aMIMEType, aURI);
}

nsresult
nsObjectLoadingContent::Instantiate(nsIObjectFrame* aFrame,
                                    const nsACString& aMIMEType,
                                    nsIURI* aURI)
{
  NS_ASSERTION(aFrame, "Must have a frame here");

  // We're instantiating now, invalidate any pending async instantiate
  // calls.
  mPendingInstantiateEvent = nsnull;

  // Mark that we're instantiating now so that we don't end up
  // re-entering instantiation code.
  PRBool oldInstantiatingValue = mInstantiating;
  mInstantiating = PR_TRUE;

  nsCString typeToUse(aMIMEType);
  if (typeToUse.IsEmpty() && aURI) {
    IsPluginEnabledByExtension(aURI, typeToUse);
  }

  nsCOMPtr<nsIContent> thisContent = 
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  NS_ASSERTION(thisContent, "must be a content");
  
  nsCOMPtr<nsIURI> baseURI;
  if (!aURI) {
    // We need some URI. If we have nothing else, use the base URI.
    // XXX(biesi): The code used to do this. Not sure why this is correct...
    GetObjectBaseURI(thisContent, getter_AddRefs(baseURI));
    aURI = baseURI;
  }

  nsIFrame *nsiframe = do_QueryFrame(aFrame);
  nsWeakFrame weakFrame(nsiframe);

  // We'll always have a type or a URI by the time we get here
  NS_ASSERTION(aURI || !typeToUse.IsEmpty(), "Need a URI or a type");
  LOG(("OBJLC [%p]: Calling [%p]->Instantiate(<%s>, %p)\n", this, aFrame,
       typeToUse.get(), aURI));
  nsresult rv = aFrame->Instantiate(typeToUse.get(), aURI);

  mInstantiating = oldInstantiatingValue;

  nsRefPtr<nsNPAPIPluginInstance> pluginInstance;
  if (weakFrame.IsAlive()) {
    aFrame->GetPluginInstance(getter_AddRefs(pluginInstance));
  }
  if (pluginInstance) {
    nsCOMPtr<nsIPluginTag> pluginTag;
    nsCOMPtr<nsIPluginHost> host(do_GetService(MOZ_PLUGIN_HOST_CONTRACTID));
    static_cast<nsPluginHost*>(host.get())->
      GetPluginTagForInstance(pluginInstance, getter_AddRefs(pluginTag));

    nsCOMPtr<nsIBlocklistService> blocklist =
      do_GetService("@mozilla.org/extensions/blocklist;1");
    if (blocklist) {
      PRUint32 blockState = nsIBlocklistService::STATE_NOT_BLOCKED;
      blocklist->GetPluginBlocklistState(pluginTag, EmptyString(),
                                         EmptyString(), &blockState);
      if (blockState == nsIBlocklistService::STATE_OUTDATED)
        FirePluginError(thisContent, ePluginOutdated);
    }
  }

  return rv;
}

/* static */ PluginSupportState
nsObjectLoadingContent::GetPluginSupportState(nsIContent* aContent,
                                              const nsCString& aContentType)
{
  if (!aContent->IsHTML()) {
    return ePluginOtherState;
  }

  if (aContent->Tag() == nsGkAtoms::embed ||
      aContent->Tag() == nsGkAtoms::applet) {
    return GetPluginDisabledState(aContentType);
  }

  PRBool hasAlternateContent = PR_FALSE;

  // Search for a child <param> with a pluginurl name
  PRUint32 count = aContent->GetChildCount();
  for (PRUint32 i = 0; i < count; ++i) {
    nsIContent* child = aContent->GetChildAt(i);
    NS_ASSERTION(child, "GetChildCount lied!");

    if (child->IsHTML() &&
        child->Tag() == nsGkAtoms::param) {
      if (child->AttrValueIs(kNameSpaceID_None, nsGkAtoms::name,
                             NS_LITERAL_STRING("pluginurl"), eIgnoreCase)) {
        return GetPluginDisabledState(aContentType);
      }
    } else if (!hasAlternateContent) {
      hasAlternateContent =
        nsStyleUtil::IsSignificantChild(child, PR_TRUE, PR_FALSE);
    }
  }

  return hasAlternateContent ? ePluginOtherState :
    GetPluginDisabledState(aContentType);
}

/* static */ PluginSupportState
nsObjectLoadingContent::GetPluginDisabledState(const nsCString& aContentType)
{
  nsCOMPtr<nsIPluginHost> pluginHostCOM(do_GetService(MOZ_PLUGIN_HOST_CONTRACTID));
  nsPluginHost *pluginHost = static_cast<nsPluginHost*>(pluginHostCOM.get());
  if (!pluginHost) {
    return ePluginUnsupported;
  }

  nsresult rv = pluginHost->IsPluginEnabledForType(aContentType.get());
  if (rv == NS_ERROR_PLUGIN_DISABLED)
    return ePluginDisabled;
  if (rv == NS_ERROR_PLUGIN_BLOCKLISTED)
    return ePluginBlocklisted;
  return ePluginUnsupported;
}

void
nsObjectLoadingContent::CreateStaticClone(nsObjectLoadingContent* aDest) const
{
  nsImageLoadingContent::CreateStaticImageClone(aDest);

  aDest->mType = mType;
  nsObjectLoadingContent* thisObj = const_cast<nsObjectLoadingContent*>(this);
  if (thisObj->mPrintFrame.IsAlive()) {
    aDest->mPrintFrame = thisObj->mPrintFrame;
  } else {
    nsIObjectFrame* frame =
      const_cast<nsObjectLoadingContent*>(this)->GetExistingFrame(eDontFlush);
    nsIFrame* f = do_QueryFrame(frame);
    aDest->mPrintFrame = f;
  }

  if (mFrameLoader) {
    nsCOMPtr<nsIContent> content =
      do_QueryInterface(static_cast<nsIImageLoadingContent*>((aDest)));
    nsFrameLoader* fl = nsFrameLoader::Create(content, PR_FALSE);
    if (fl) {
      aDest->mFrameLoader = fl;
      mFrameLoader->CreateStaticClone(fl);
    }
  }
}

NS_IMETHODIMP
nsObjectLoadingContent::GetPrintFrame(nsIFrame** aFrame)
{
  *aFrame = mPrintFrame.GetFrame();
  return NS_OK;
}

NS_IMETHODIMP
nsObjectLoadingContent::PluginCrashed(nsIPluginTag* aPluginTag,
                                      const nsAString& pluginDumpID,
                                      const nsAString& browserDumpID,
                                      PRBool submittedCrashReport)
{
  AutoNotifier notifier(this, PR_TRUE);
  UnloadContent();
  mFallbackReason = ePluginCrashed;
  nsCOMPtr<nsIContent> thisContent = do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));

  // Note that aPluginTag in invalidated after we're called, so copy 
  // out any data we need now.
  nsCAutoString pluginName;
  aPluginTag->GetName(pluginName);
  nsCAutoString pluginFilename;
  aPluginTag->GetFilename(pluginFilename);

  nsCOMPtr<nsIRunnable> ev = new nsPluginCrashedEvent(thisContent,
                                                      pluginDumpID,
                                                      browserDumpID,
                                                      NS_ConvertUTF8toUTF16(pluginName),
                                                      NS_ConvertUTF8toUTF16(pluginFilename),
                                                      submittedCrashReport);
  nsresult rv = NS_DispatchToCurrentThread(ev);
  if (NS_FAILED(rv)) {
    NS_WARNING("failed to dispatch nsPluginCrashedEvent");
  }
  return NS_OK;
}