cc: Add receiver for CompositorFrameAck in LayerTreeHostImpl and forward it to the renderer.

BUG=146080
R=piman

Review URL: https://codereview.chromium.org/11472004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@171895 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/cc/renderer.h b/cc/renderer.h
index b7395374..981679c 100644
--- a/cc/renderer.h
+++ b/cc/renderer.h
@@ -13,6 +13,7 @@
 
 namespace cc {
 
+class CompositorFrameAck;
 class ScopedResource;
 
 class CC_EXPORT RendererClient {
@@ -49,6 +50,7 @@
     int viewportHeight() { return viewportSize().height(); }
 
     virtual void viewportChanged() { }
+    virtual void receiveCompositorFrameAck(const CompositorFrameAck&) { }
 
     virtual void decideRenderPassAllocationsForFrame(const RenderPassList&) { }
     virtual bool haveCachedResourcesForRenderPassId(RenderPass::Id) const;