cc: Cleanup class/struct forward declarations

cc/trees/layer_tree_host_client.h

 // 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.
 
 #ifndef CC_TREES_LAYER_TREE_HOST_CLIENT_H_
 #define CC_TREES_LAYER_TREE_HOST_CLIENT_H_
 
 #include <memory>
 
 #include "base/memory/ref_counted.h"
 
 namespace gfx {
-class Vector2d;
 class Vector2dF;
 }
 
 namespace cc {
-class ContextProvider;
-class InputHandlerClient;
 class CompositorFrameSink;
 struct BeginFrameArgs;
 
 class LayerTreeHostClient {
  public:
   virtual void WillBeginMainFrame() = 0;
   // Marks finishing compositing-related tasks on the main thread. In threaded
   // mode, this corresponds to DidCommit().
   virtual void BeginMainFrame(const BeginFrameArgs& args) = 0;
   virtual void BeginMainFrameNotExpectedSoon() = 0;
@@ skipping 29 matching lines @@
   virtual void DidReceiveCompositorFrameAck() = 0;
   virtual void DidCompletePageScaleAnimation() = 0;
 
  protected:
   virtual ~LayerTreeHostClient() {}
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_CLIENT_H_