Remove unnecessary LayerTreeBuildHelper from ContentViewRenderView

content/public/browser/android/layer_tree_build_helper.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 CONTENT_PUBLIC_BROWSER_ANDROID_LAYER_TREE_BUILD_HELPER_H_
-#define CONTENT_PUBLIC_BROWSER_ANDROID_LAYER_TREE_BUILD_HELPER_H_
-
-#include "base/memory/ref_counted.h"
-
-namespace cc {
-class Layer;
-}
-
-namespace content {
-
-// A Helper class to build a layer tree to be composited
-// given a content root layer.
-class LayerTreeBuildHelper {
- public:
-  LayerTreeBuildHelper() {};
-  virtual scoped_refptr<cc::Layer> GetLayerTree(
-      scoped_refptr<cc::Layer> content_root_layer) = 0;
-  virtual ~LayerTreeBuildHelper() {};
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(LayerTreeBuildHelper);
-};
-
-}
-
-#endif  // CONTENT_PUBLIC_BROWSER_ANDROID_LAYER_TREE_BUILD_HELPER_H_