Remove CompositeAndReadback from LayerTreeHost(Impl) and the Proxys.

cc/trees/layer_tree_host.h

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_TREES_LAYER_TREE_HOST_H_
 #define CC_TREES_LAYER_TREE_HOST_H_
 
 #include <limits>
 #include <list>
 #include <set>
@@ skipping 113 matching lines @@
 
   LayerTreeHostClient* client() { return client_; }
   const base::WeakPtr<InputHandler>& GetInputHandler() {
     return input_handler_weak_ptr_;
   }
 
   void NotifyInputThrottledUntilCommit();
 
   void Composite(base::TimeTicks frame_begin_time);
 
-  // Composites and attempts to read back the result into the provided
-  // buffer. If it wasn't possible, e.g. due to context lost, will return
-  // false.
-  bool CompositeAndReadback(void* pixels,
-                            const gfx::Rect& rect_in_device_viewport);
-
   void FinishAllRendering();
 
   void SetDeferCommits(bool defer_commits);
 
   // Test only hook
   virtual void DidDeferCommit();
 
   int source_frame_number() const { return source_frame_number_; }
 
   void SetNeedsDisplayOnAllLayers();
@@ skipping 299 matching lines @@
 
   ScopedPtrVector<SwapPromise> swap_promise_list_;
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_