cc: Cleanup class/struct forward declarations

cc/input/browser_controls_offset_manager.h

 // Copyright 2016 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_INPUT_BROWSER_CONTROLS_OFFSET_MANAGER_H_
 #define CC_INPUT_BROWSER_CONTROLS_OFFSET_MANAGER_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "cc/input/browser_controls_state.h"
 #include "cc/layers/layer_impl.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/geometry/vector2d_f.h"
 
 namespace cc {
 
-class LayerTreeImpl;
 class BrowserControlsOffsetManagerClient;
 
 // Manages the position of the browser controls.
 class CC_EXPORT BrowserControlsOffsetManager
     : public base::SupportsWeakPtr<BrowserControlsOffsetManager> {
  public:
   enum AnimationDirection { NO_ANIMATION, SHOWING_CONTROLS, HIDING_CONTROLS };
 
   static std::unique_ptr<BrowserControlsOffsetManager> Create(
       BrowserControlsOffsetManagerClient* client,
@@ skipping 77 matching lines @@
   float controls_hide_threshold_;
 
   bool pinch_gesture_active_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserControlsOffsetManager);
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_BROWSER_CONTROLS_OFFSET_MANAGER_H_