Bug 783066: Paint the backgrounds of remote subdocuments like we paint those of same-process subdocuments. r=roc

dom/ipc/TabChild.cpp

@@ -677,6 +677,23 @@ TabChild::~TabChild()
     }
 }
 
+bool
+TabChild::IsRootContentDocument()
+{
+    if (!mIsBrowserElement && mAppId == nsIScriptSecurityManager::NO_APP_ID) {
+        // We're the child side of a <xul:browser remote=true>.  This
+        // is always a root content document.
+        return true;
+    }
+
+    // Otherwise, we're the child side of an <html:browser
+    // remote=true> or <html:app remote=true>.  Because of bug 761935,
+    // these can't be nested within another <html:app remote=true>, so
+    // we assume that we can't be a root content document.  When that
+    // bug is fixed, we need to revisit that assumption.
+    return false;
+}
+
 bool
 TabChild::RecvLoadURL(const nsCString& uri)
 {

dom/ipc/TabChild.h

@@ -164,6 +164,8 @@ public:
 
     uint32_t GetAppId() { return mAppId; }
 
+    bool IsRootContentDocument();
+
     NS_DECL_ISUPPORTS
     NS_DECL_NSIWEBBROWSERCHROME
     NS_DECL_NSIWEBBROWSERCHROME2

layout/base/nsPresContext.cpp

@@ -5,6 +5,8 @@
 
 /* a presentation of a document, part 1 */
 
+#include "base/basictypes.h"
+
 #include "nsCOMPtr.h"
 #include "nsPresContext.h"
 #include "nsIPresShell.h"
@@ -63,6 +65,8 @@
 #include "nsDOMMediaQueryList.h"
 #include "nsSMILAnimationController.h"
 #include "mozilla/css/ImageLoader.h"
+#include "mozilla/dom/PBrowserChild.h"
+#include "mozilla/dom/TabChild.h"
 
 #ifdef IBMBIDI
 #include "nsBidiPresUtils.h"
@@ -2340,6 +2344,21 @@ nsPresContext::IsRootContentDocument()
   return (f && f->PresContext()->IsChrome());
 }
 
+bool
+nsPresContext::IsCrossProcessRootContentDocument()
+{
+  if (!IsRootContentDocument()) {
+    return false;
+  }
+
+  if (XRE_GetProcessType() == GeckoProcessType_Default) {
+    return true;
+  }
+
+  TabChild* tabChild = GetTabChildFrom(mShell);
+  return (tabChild && tabChild->IsRootContentDocument());
+}
+
 nsRootPresContext::nsRootPresContext(nsIDocument* aDocument,
                                      nsPresContextType aType)
   : nsPresContext(aDocument, aType),

layout/base/nsPresContext.h

@@ -897,6 +897,7 @@ public:
   }
 
   bool IsRootContentDocument();
+  bool IsCrossProcessRootContentDocument();
 
 protected:
   friend class nsRunnableMethod<nsPresContext>;

layout/base/nsPresShell.cpp

@@ -4927,7 +4927,7 @@ void PresShell::UpdateCanvasBackground()
                                                rootStyleFrame,
                                                drawBackgroundImage,
                                                drawBackgroundColor);
-    if (GetPresContext()->IsRootContentDocument() &&
+    if (GetPresContext()->IsCrossProcessRootContentDocument() &&
         !IsTransparentContainerElement(mPresContext)) {
       mCanvasBackgroundColor =
         NS_ComposeColors(GetDefaultBackgroundColorToDraw(), mCanvasBackgroundColor);

widget/xpwidgets/PuppetWidget.h

@@ -133,13 +133,20 @@ public:
   // nsBaseWidget methods we override
   //
 
-//NS_IMETHOD              CaptureMouse(bool aCapture);
+  // Documents loaded in child processes are always subdocuments of
+  // other docs in an ancestor process.  To ensure that the
+  // backgrounds of those documents are painted like those of
+  // same-process subdocuments, we force the widget here to be
+  // transparent, which in turn will cause layout to use a transparent
+  // backstop background color.
+  virtual nsTransparencyMode GetTransparencyMode() MOZ_OVERRIDE
+  { return eTransparencyTransparent; }
+
   virtual LayerManager*
   GetLayerManager(PLayersChild* aShadowManager = nullptr,
                   LayersBackend aBackendHint = mozilla::layers::LAYERS_NONE,
                   LayerManagerPersistence aPersistence = LAYER_MANAGER_CURRENT,
                   bool* aAllowRetaining = nullptr);
-//  virtual nsDeviceContext* GetDeviceContext();
   virtual gfxASurface*      GetThebesSurface();
 
   NS_IMETHOD ResetInputState();