Avoid exposing cc::Layer tree to CompositorProxy

third_party/WebKit/Source/platform/graphics/CompositorMutableState.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 CompositorMutableState_h
 #define CompositorMutableState_h
 
 #include "platform/PlatformExport.h"
 
 class SkMatrix44;
 
-namespace cc {
-class LayerImpl;
-}  // namespace cc
-
 namespace blink {
 
+class CompositorMutableProperties;
 class CompositorMutation;
 
 // This class wraps the compositor-owned, mutable state for a single element.
 class PLATFORM_EXPORT CompositorMutableState {
  public:
-  CompositorMutableState(CompositorMutation*,
-                         cc::LayerImpl* main,
-                         cc::LayerImpl* scroll);
+  CompositorMutableState(CompositorMutation*, CompositorMutableProperties*);
   ~CompositorMutableState();
 
   double Opacity() const;
   void SetOpacity(double);
 
   const SkMatrix44& Transform() const;
   void SetTransform(const SkMatrix44&);
 
   float ScrollLeft() const;
   void SetScrollLeft(float);
 
   float ScrollTop() const;
   void SetScrollTop(float);
 
  private:
   CompositorMutation* mutation_;
-  cc::LayerImpl* main_layer_;
-  cc::LayerImpl* scroll_layer_;
+  CompositorMutableProperties* properties_;
 };
 
 }  // namespace blink
 
 #endif  // CompositorMutableState_h