CC Animations: Make LayerAnimationController creation optional

chrome/browser/android/compositor/layer/layer.h

 // Copyright 2014 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 CHROME_BROWSER_ANDROID_COMPOSITOR_LAYER_LAYER_H_
 #define CHROME_BROWSER_ANDROID_COMPOSITOR_LAYER_LAYER_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/layers/layer.h"
 #include "cc/output/filter_operations.h"
 #include "ui/gfx/geometry/size.h"
 
+namespace cc {
+class LayerSettings;
+}
+
 namespace chrome {
 namespace android {
 
 // A simple wrapper for cc::Layer. You can override this to contain
 // layers and add functionalities to it.
 class Layer : public base::RefCounted<Layer> {
  public:
   virtual scoped_refptr<cc::Layer> layer() = 0;
 
  protected:
   Layer() {}
   virtual ~Layer() {}
 
  private:
   friend class base::RefCounted<Layer>;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace android
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_ANDROID_COMPOSITOR_LAYER_LAYER_H_