Bug 637901 - Don't trash our cached ImageContainer unless the retained layer manager has changed. r=tnikkel a=blocking2.0

content/base/public/nsContentUtils.h

@@ -1699,12 +1699,12 @@ public:
    * a presentation with an associated widget, and use that widget's
    * layer manager.
    *
-   * If one can't be found, a BasicLayerManager is created and returned.
-   *
    * @param aDoc the document for which to return a layer manager.
+   * @param aAllowRetaining an outparam that states whether the returned
+   * layer manager should be used for retained layers
    */
   static already_AddRefed<mozilla::layers::LayerManager>
-  LayerManagerForDocument(nsIDocument *aDoc);
+  LayerManagerForDocument(nsIDocument *aDoc, bool *aAllowRetaining = nsnull);
 
   /**
    * Returns a layer manager to use for the given document. Basically we
@@ -1716,12 +1716,12 @@ public:
    * forseeable future. This function should be used carefully as it may change
    * the document's layer manager.
    *
-   * If one can't be found, a BasicLayerManager is created and returned.
-   *
    * @param aDoc the document for which to return a layer manager.
+   * @param aAllowRetaining an outparam that states whether the returned
+   * layer manager should be used for retained layers
    */
   static already_AddRefed<mozilla::layers::LayerManager>
-  PersistentLayerManagerForDocument(nsIDocument *aDoc);
+  PersistentLayerManagerForDocument(nsIDocument *aDoc, bool *aAllowRetaining = nsnull);
 
   /**
    * Determine whether a content node is focused or not,

content/base/src/nsContentUtils.cpp

@@ -6354,7 +6354,8 @@ static nsIView* GetDisplayRootFor(nsIView* aView)
 }
 
 static already_AddRefed<LayerManager>
-LayerManagerForDocumentInternal(nsIDocument *aDoc, bool aRequirePersistent)
+LayerManagerForDocumentInternal(nsIDocument *aDoc, bool aRequirePersistent,
+                                bool* aAllowRetaining)
 {
   nsIDocument* doc = aDoc;
   nsIDocument* displayDoc = doc->GetDisplayDocument();
@@ -6394,7 +6395,8 @@ LayerManagerForDocumentInternal(nsIDocument *aDoc, bool aRequirePersistent)
             nsRefPtr<LayerManager> manager =
               static_cast<nsIWidget_MOZILLA_2_0_BRANCH*>(widget)->
                 GetLayerManager(aRequirePersistent ? nsIWidget_MOZILLA_2_0_BRANCH::LAYER_MANAGER_PERSISTENT : 
-                                                     nsIWidget_MOZILLA_2_0_BRANCH::LAYER_MANAGER_CURRENT);
+                                                     nsIWidget_MOZILLA_2_0_BRANCH::LAYER_MANAGER_CURRENT,
+                                aAllowRetaining);
             return manager.forget();
           }
         }
@@ -6406,15 +6408,15 @@ LayerManagerForDocumentInternal(nsIDocument *aDoc, bool aRequirePersistent)
 }
 
 already_AddRefed<LayerManager>
-nsContentUtils::LayerManagerForDocument(nsIDocument *aDoc)
+nsContentUtils::LayerManagerForDocument(nsIDocument *aDoc, bool *aAllowRetaining)
 {
-  return LayerManagerForDocumentInternal(aDoc, false);
+  return LayerManagerForDocumentInternal(aDoc, false, aAllowRetaining);
 }
 
 already_AddRefed<LayerManager>
-nsContentUtils::PersistentLayerManagerForDocument(nsIDocument *aDoc)
+nsContentUtils::PersistentLayerManagerForDocument(nsIDocument *aDoc, bool *aAllowRetaining)
 {
-  return LayerManagerForDocumentInternal(aDoc, true);
+  return LayerManagerForDocumentInternal(aDoc, true, aAllowRetaining);
 }
 
 bool

layout/generic/nsObjectFrame.cpp

@@ -1642,7 +1642,7 @@ nsObjectFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
   #endif
     }
 
-    ImageContainer* container = GetImageContainer();
+    nsRefPtr<ImageContainer> container = GetImageContainer();
     nsRefPtr<Image> currentImage = container ? container->GetCurrentImage() : nsnull;
     if (!currentImage || !isVisible ||
         container->GetCurrentSize() != gfxIntSize(window->width, window->height)) {
@@ -1884,31 +1884,43 @@ nsObjectFrame::PrintPlugin(nsIRenderingContext& aRenderingContext,
                    nsnull, status);  // DidReflow will take care of it
 }
 
-ImageContainer*
+already_AddRefed<ImageContainer>
 nsObjectFrame::GetImageContainer(LayerManager* aManager)
 {
   nsRefPtr<LayerManager> manager = aManager;
+  bool retain = false;
 
   if (!manager) {
-    manager = nsContentUtils::LayerManagerForDocument(mContent->GetOwnerDoc());
+    manager = nsContentUtils::LayerManagerForDocument(mContent->GetOwnerDoc(), &retain);
   }
   if (!manager) {
     return nsnull;
   }
+  
+  nsRefPtr<ImageContainer> container;
 
   // XXX - in the future image containers will be manager independent and
   // we can remove the manager equals check and only check the backend type.
   if (mImageContainer) {
     if ((!mImageContainer->Manager() || mImageContainer->Manager() == manager) &&
-        mImageContainer->GetBackendType() == manager->GetBackendType())
-      return mImageContainer;
-    // Clear current image before we reset mImageContainer. Only mImageContainer
-    // is allowed to contain the image for this plugin.
-    mImageContainer->SetCurrentImage(nsnull);
+        mImageContainer->GetBackendType() == manager->GetBackendType()) {
+      container = mImageContainer;
+      return container.forget();
+    }
   }
 
-  mImageContainer = manager->CreateImageContainer();
-  return mImageContainer;
+  container = manager->CreateImageContainer();
+
+  if (retain) {
+    // Clear current image before we reset mImageContainer. Only mImageContainer
+    // is allowed to contain the image for this plugin.
+    if (mImageContainer) {
+      mImageContainer->SetCurrentImage(nsnull);
+    }
+    mImageContainer = container;
+  }
+
+  return container.forget();
 }
 
 nsRect

layout/generic/nsObjectFrame.h

@@ -191,7 +191,7 @@ public:
   virtual LayerState GetLayerState(nsDisplayListBuilder* aBuilder,
                                    LayerManager* aManager);
 
-  ImageContainer* GetImageContainer(LayerManager* aManager = nsnull);
+  already_AddRefed<ImageContainer> GetImageContainer(LayerManager* aManager = nsnull);
   /**
    * Get the rectangle (relative to this frame) which it will paint. Normally
    * the frame's content-box but may be smaller if the plugin is rendering