Bug 976766 - Clear layer's buffers when ClearCachedResources() r=nical

gfx/layers/client/CanvasClient.h

@@ -57,6 +57,8 @@ public:
 
   virtual ~CanvasClient() {}
 
+  virtual void Clear() {};
+
   virtual void Update(gfx::IntSize aSize, ClientCanvasLayer* aLayer) = 0;
 
   virtual void Updated() { }
@@ -80,6 +82,11 @@ public:
     return TextureInfo(COMPOSITABLE_IMAGE);
   }
 
+  virtual void Clear() MOZ_OVERRIDE
+  {
+    mBuffer = nullptr;
+  }
+
   virtual void Update(gfx::IntSize aSize, ClientCanvasLayer* aLayer) MOZ_OVERRIDE;
 
   virtual bool AddTextureClient(TextureClient* aTexture) MOZ_OVERRIDE
@@ -113,6 +120,11 @@ public:
     return TextureInfo(COMPOSITABLE_IMAGE);
   }
 
+  virtual void Clear() MOZ_OVERRIDE
+  {
+    mBuffer = nullptr;
+  }
+
   virtual void Update(gfx::IntSize aSize, ClientCanvasLayer* aLayer) MOZ_OVERRIDE;
 
   virtual void OnDetach() MOZ_OVERRIDE

gfx/layers/client/ClientCanvasLayer.h

@@ -56,6 +56,13 @@ public:
 
   virtual void RenderLayer();
 
+  virtual void ClearCachedResources()
+  {
+    if (mCanvasClient) {
+      mCanvasClient->Clear();
+    }
+  }
+
   virtual void FillSpecificAttributes(SpecificLayerAttributes& aAttrs)
   {
     aAttrs = CanvasLayerAttributes(mFilter, mBounds);

gfx/layers/client/ContentClient.h

@@ -206,7 +206,12 @@ public:
   typedef RotatedContentBuffer::PaintState PaintState;
   typedef RotatedContentBuffer::ContentType ContentType;
 
-  virtual void Clear() { RotatedContentBuffer::Clear(); }
+  virtual void Clear()
+  {
+    RotatedContentBuffer::Clear();
+    mTextureClient = nullptr;
+    mTextureClientOnWhite = nullptr;
+  }
 
   virtual PaintState BeginPaintBuffer(ThebesLayer* aLayer,
                                       uint32_t aFlags) MOZ_OVERRIDE
@@ -424,6 +429,13 @@ public:
   }
   virtual ~ContentClientDoubleBuffered() {}
 
+  virtual void Clear() MOZ_OVERRIDE
+  {
+    ContentClientRemoteBuffer::Clear();
+    mFrontClient = nullptr;
+    mFrontClientOnWhite = nullptr;
+  }
+
   virtual void SwapBuffers(const nsIntRegion& aFrontUpdatedRegion) MOZ_OVERRIDE;
 
   virtual void PrepareFrame() MOZ_OVERRIDE;