Remove CompositeAndReadback from LayerTreeHost(Impl) and the Proxys.

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index d246a030087e7ab8b206ce06d11745f1e6445652..81db9232bb63dcabfd17ddf582ff3ae6b333c290 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -192,9 +192,7 @@ class CC_EXPORT LayerTreeHostImpl
   // to avoid displaying the frame. If PrepareToDraw is called, DidDrawAllLayers
   // must also be called, regardless of whether DrawLayers is called between the
   // two.
-  virtual DrawSwapReadbackResult::DrawResult PrepareToDraw(
-      FrameData* frame,
-      const gfx::Rect& damage_rect);
+  virtual DrawSwapReadbackResult::DrawResult PrepareToDraw(FrameData* frame);

[brianderson, 2014/05/10 00:47:53]

I would say rename this to DrawSwapResult, but Simon is in the process of
removing this already.

[danakj, 2014/05/10 15:30:55]

I was planning to change this to a bool or rename it etc in next CL since this
would require changes in the scheduler. 

   virtual void DrawLayers(FrameData* frame, base::TimeTicks frame_begin_time);
   // Must be called if and only if PrepareToDraw was called.
   void DidDrawAllLayers(const FrameData& frame);
@@ -282,8 +280,6 @@ class CC_EXPORT LayerTreeHostImpl
   virtual void WillBeginImplFrame(const BeginFrameArgs& args);
   void DidModifyTilePriorities();
 
-  void Readback(void* pixels, const gfx::Rect& rect_in_device_viewport);
-
   LayerTreeImpl* active_tree() { return active_tree_.get(); }
   const LayerTreeImpl* active_tree() const { return active_tree_.get(); }
   LayerTreeImpl* pending_tree() { return pending_tree_.get(); }
@@ -380,7 +376,7 @@ class CC_EXPORT LayerTreeHostImpl
   const LayerTreeDebugState& debug_state() const { return debug_state_; }
 
   class CC_EXPORT CullRenderPassesWithNoQuads {
- public:
+   public:
     bool ShouldRemoveRenderPass(const RenderPassDrawQuad& quad,
                                 const FrameData& frame) const;