Bug 755533 - Ensure we fire canplaythrough if the media's channel is suspended before metadata is loaded. r=roc

content/html/content/public/nsHTMLMediaElement.h

@@ -159,6 +159,10 @@ public:
   // (no data has arrived for a while).
   void DownloadStalled();
 
+  // Called by the media decoder to indicate whether the media cache has
+  // suspended the channel.
+  void NotifySuspendedByCache(bool aIsSuspended);
+
   // Called when a "MozAudioAvailable" event listener is added. The media
   // element will then notify its decoder that it needs to make a copy of
   // the audio data sent to hardware and dispatch it in "mozaudioavailable"
@@ -833,7 +837,7 @@ protected:
   // due to loading a preload:none media. When true, the resource we'll
   // load when the user initiates either playback or an explicit load is
   // stored in mPreloadURI.
-  bool mLoadIsSuspended;
+  bool mSuspendedForPreloadNone;
 
   // True if a same-origin check has been done for the media element and resource.
   bool mMediaSecurityVerified;
@@ -843,6 +847,9 @@ protected:
 
   // True if the media has an audio track
   bool mHasAudio;
+
+  // True if the media's channel's download has been suspended.
+  bool mDownloadSuspendedByCache;
 };
 
 #endif

content/html/content/src/nsHTMLMediaElement.cpp

@@ -593,7 +593,8 @@ void nsHTMLMediaElement::AbortExistingLoads()
   mSuspendedAfterFirstFrame = false;
   mAllowSuspendAfterFirstFrame = true;
   mHaveQueuedSelectResource = false;
-  mLoadIsSuspended = false;
+  mSuspendedForPreloadNone = false;
+  mDownloadSuspendedByCache = false;
   mSourcePointer = nsnull;
 
   // TODO: The playback rate must be set to the default playback rate.
@@ -905,7 +906,7 @@ void nsHTMLMediaElement::LoadFromSourceChildren()
 
 void nsHTMLMediaElement::SuspendLoad()
 {
-  mLoadIsSuspended = true;
+  mSuspendedForPreloadNone = true;
   mNetworkState = nsIDOMHTMLMediaElement::NETWORK_IDLE;
   DispatchAsyncEvent(NS_LITERAL_STRING("suspend"));
   ChangeDelayLoadStatus(false);
@@ -913,8 +914,9 @@ void nsHTMLMediaElement::SuspendLoad()
 
 void nsHTMLMediaElement::ResumeLoad(PreloadAction aAction)
 {
-  NS_ASSERTION(mLoadIsSuspended, "Can only resume preload if halted for one");
-  mLoadIsSuspended = false;
+  NS_ASSERTION(mSuspendedForPreloadNone,
+    "Must be halted for preload:none to resume from preload:none suspended load.");
+  mSuspendedForPreloadNone = false;
   mPreloadAction = aAction;
   ChangeDelayLoadStatus(true);
   mNetworkState = nsIDOMHTMLMediaElement::NETWORK_LOADING;
@@ -987,7 +989,7 @@ void nsHTMLMediaElement::UpdatePreloadAction()
 
   mPreloadAction = nextAction;
   if (nextAction == nsHTMLMediaElement::PRELOAD_ENOUGH) {
-    if (mLoadIsSuspended) {
+    if (mSuspendedForPreloadNone) {
       // Our load was previouly suspended due to the media having preload
       // value "none". The preload value has changed to preload:auto, so
       // resume the load.
@@ -1001,7 +1003,7 @@ void nsHTMLMediaElement::UpdatePreloadAction()
   } else if (nextAction == nsHTMLMediaElement::PRELOAD_METADATA) {
     // Ensure that the video can be suspended after first frame.
     mAllowSuspendAfterFirstFrame = true;
-    if (mLoadIsSuspended) {
+    if (mSuspendedForPreloadNone) {
       // Our load was previouly suspended due to the media having preload
       // value "none". The preload value has changed to preload:metadata, so
       // resume the load. We'll pause the load again after we've read the
@@ -1650,10 +1652,11 @@ nsHTMLMediaElement::nsHTMLMediaElement(already_AddRefed<nsINodeInfo> aNodeInfo)
     mHasPlayedOrSeeked(false),
     mHasSelfReference(false),
     mShuttingDown(false),
-    mLoadIsSuspended(false),
+    mSuspendedForPreloadNone(false),
     mMediaSecurityVerified(false),
     mCORSMode(CORS_NONE),
-    mHasAudio(false)
+    mHasAudio(false),
+    mDownloadSuspendedByCache(false)
 {
 #ifdef PR_LOGGING
   if (!gMediaElementLog) {
@@ -1733,7 +1736,7 @@ NS_IMETHODIMP nsHTMLMediaElement::Play()
     nsresult rv = Load();
     NS_ENSURE_SUCCESS(rv, rv);
   }
-  if (mLoadIsSuspended) {
+  if (mSuspendedForPreloadNone) {
     ResumeLoad(PRELOAD_ENOUGH);
   }
   // Even if we just did Load() or ResumeLoad(), we could already have a decoder
@@ -2636,6 +2639,20 @@ void nsHTMLMediaElement::FirstFrameLoaded(bool aResourceFullyLoaded)
       mPreloadAction == nsHTMLMediaElement::PRELOAD_METADATA) {
     mSuspendedAfterFirstFrame = true;
     mDecoder->Suspend();
+  } else if (mLoadedFirstFrame &&
+             mDownloadSuspendedByCache && 
+             mDecoder &&
+             !mDecoder->IsEnded()) {
+    // We've already loaded the first frame, and the decoder has signalled
+    // that the download has been suspended by the media cache. So move
+    // readyState into HAVE_ENOUGH_DATA, in case there's script waiting
+    // for a "canplaythrough" event; without this forced transition, we will
+    // never fire the "canplaythrough" event if the media cache is so small
+    // that the download was suspended before the first frame was loaded.
+    // Don't force this transition if the decoder is in ended state; the
+    // readyState should remain at HAVE_CURRENT_DATA in this case.
+    ChangeReadyState(nsIDOMHTMLMediaElement::HAVE_ENOUGH_DATA);
+    return;
   }
 }
 
@@ -2734,6 +2751,7 @@ void nsHTMLMediaElement::PlaybackEnded()
 void nsHTMLMediaElement::SeekStarted()
 {
   DispatchAsyncEvent(NS_LITERAL_STRING("seeking"));
+  ChangeReadyState(nsIDOMHTMLMediaElement::HAVE_METADATA);
   FireTimeUpdate(false);
 }
 
@@ -2746,6 +2764,11 @@ void nsHTMLMediaElement::SeekCompleted()
   AddRemoveSelfReference();
 }
 
+void nsHTMLMediaElement::NotifySuspendedByCache(bool aIsSuspended)
+{
+  mDownloadSuspendedByCache = aIsSuspended;
+}
+
 void nsHTMLMediaElement::DownloadSuspended()
 {
   DispatchAsyncEvent(NS_LITERAL_STRING("progress"));
@@ -2786,6 +2809,21 @@ void nsHTMLMediaElement::UpdateReadyStateForData(NextFrameStatus aNextFrame)
     return;
   }
 
+  if (mReadyState > nsIDOMHTMLMediaElement::HAVE_METADATA &&
+      mDownloadSuspendedByCache &&
+      mDecoder &&
+      !mDecoder->IsEnded()) {
+    // The decoder has signalled that the download has been suspended by the
+    // media cache. So move readyState into HAVE_ENOUGH_DATA, in case there's
+    // script waiting for a "canplaythrough" event; without this forced
+    // transition, we will never fire the "canplaythrough" event if the
+    // media cache is too small, and scripts are bound to fail. Don't force
+    // this transition if the decoder is in ended state; the readyState
+    // should remain at HAVE_CURRENT_DATA in this case.
+    ChangeReadyState(nsIDOMHTMLMediaElement::HAVE_ENOUGH_DATA);
+    return;
+  }
+
   if (aNextFrame != NEXT_FRAME_AVAILABLE) {
     ChangeReadyState(nsIDOMHTMLMediaElement::HAVE_CURRENT_DATA);
     if (!mWaitingFired && aNextFrame == NEXT_FRAME_UNAVAILABLE_BUFFERING) {

content/media/nsBuiltinDecoder.cpp

@@ -647,11 +647,15 @@ void nsBuiltinDecoder::NotifySuspendedStatusChanged()
   MediaResource* activeStream;
   bool suspended = mResource->IsSuspendedByCache(&activeStream);
   
-  if (suspended && mElement) {
-    // if this is an autoplay element, we need to kick off its autoplaying
-    // now so we consume data and hopefully free up cache space
-    mElement->NotifyAutoplayDataReady();
-  }
+  if (mElement) {
+    if (suspended) {
+      // If this is an autoplay element, we need to kick off its autoplaying
+      // now so we consume data and hopefully free up cache space.
+      mElement->NotifyAutoplayDataReady();
+    }
+    mElement->NotifySuspendedByCache(suspended);
+    mElement->UpdateReadyStateForData();
+  } 
 }
 
 void nsBuiltinDecoder::NotifyBytesDownloaded()