WIP: Surface Synchronization System

cc/layers/surface_layer.h

Index: cc/layers/surface_layer.h
diff --git a/cc/layers/surface_layer.h b/cc/layers/surface_layer.h
index 6b02364106417e7af217c7f5db57a76d8d5b3dd4..2f3d6f5307a3039a8ecf438650a43c3585db5838 100644
--- a/cc/layers/surface_layer.h
+++ b/cc/layers/surface_layer.h
@@ -23,6 +23,10 @@ class CC_EXPORT SurfaceLayer : public Layer {
 
   void SetSurfaceInfo(const SurfaceInfo& surface_info);
 
+  // The current |surface_info_| becomes the |fallback_surface_info_| and the
+  // reference to the current fallback is removed.
+  void SwapSurfaceInfo(const SurfaceInfo& surface_info);
+
   // When stretch_content_to_fill_bounds is true, the scale of the embedded
   // surface is ignored and the content will be stretched to fill the bounds.
   void SetStretchContentToFillBounds(bool stretch_content_to_fill_bounds);
@@ -35,7 +39,14 @@ class CC_EXPORT SurfaceLayer : public Layer {
   scoped_refptr<SurfaceReferenceFactory> surface_reference_factory() const {
     return ref_factory_;
   }
-  const SurfaceInfo& surface_info() const { return surface_info_; }
+
+  const SurfaceInfo& primary_surface_info() const {
+    return primary_surface_info_;
+  }
+
+  const SurfaceInfo& fallback_surface_info() const {
+    return fallback_surface_info_;
+  }
 
  protected:
   explicit SurfaceLayer(scoped_refptr<SurfaceReferenceFactory> ref_factory);
@@ -43,11 +54,15 @@ class CC_EXPORT SurfaceLayer : public Layer {
 
  private:
   ~SurfaceLayer() override;
-  void RemoveCurrentReference();
+  void RemoveReference(base::Closure reference_returner);
+
+  SurfaceInfo primary_surface_info_;
+  base::Closure primary_reference_returner_;
+
+  SurfaceInfo fallback_surface_info_;
+  base::Closure fallback_reference_returner_;
 
-  SurfaceInfo surface_info_;
   scoped_refptr<SurfaceReferenceFactory> ref_factory_;
-  base::Closure reference_returner_;
   bool stretch_content_to_fill_bounds_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(SurfaceLayer);