Remove CompositeAndReadback from LayerTreeHost(Impl) and the Proxys.

cc/test/fake_proxy.cc

 // Copyright 2012 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.
 
 #include "cc/test/fake_proxy.h"
 
 namespace cc {
 
 void FakeProxy::SetLayerTreeHost(LayerTreeHost* host) {
   layer_tree_host_ = host;
 }
 
-bool FakeProxy::CompositeAndReadback(void* pixels, const gfx::Rect& rect) {
-  return true;
-}
-
 bool FakeProxy::IsStarted() const { return true; }
 
 void FakeProxy::CreateAndInitializeOutputSurface() {
   DCHECK(layer_tree_host_);
   layer_tree_host_->OnCreateAndInitializeOutputSurfaceAttempted(true);
 }
 
 const RendererCapabilities& FakeProxy::GetRendererCapabilities() const {
   return capabilities_;
 }
@@ skipping 15 matching lines @@
 }
 
 bool FakeProxy::CommitPendingForTesting() { return false; }
 
 scoped_ptr<base::Value> FakeProxy::AsValue() const {
   scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue());
   return state.PassAs<base::Value>();
 }
 
 }  // namespace cc