Add layerTreeBuildHelper to control layer tree in ContentViewRenderView

content/browser/android/layer_tree_build_helper_impl.h

Index: content/browser/android/layer_tree_build_helper_impl.h
diff --git a/content/browser/android/layer_tree_build_helper_impl.h b/content/browser/android/layer_tree_build_helper_impl.h
new file mode 100644
index 0000000000000000000000000000000000000000..b8b1a8ab4a67f302a318b31b0f13110fa9b502d5
--- /dev/null
+++ b/content/browser/android/layer_tree_build_helper_impl.h
@@ -0,0 +1,36 @@
+// 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_BROWSER_ANDROID_LAYER_TREE_BUILD_HELPER_IMPL_H_
+#define CONTENT_BROWSER_ANDROID_LAYER_TREE_BUILD_HELPER_IMPL_H_
+
+#include "base/memory/ref_counted.h"
+#include "content/public/browser/android/layer_tree_build_helper.h"
+
+namespace cc {
+class Layer;
+}
+
+namespace content {
+
+// A Helper class to build a layer tree to be composited
+// given a content root layer.
+class LayerTreeBuildHelperImpl : public LayerTreeBuildHelper {
+ public:
+  LayerTreeBuildHelperImpl();
+
+  virtual ~LayerTreeBuildHelperImpl();
+
+  virtual scoped_refptr<cc::Layer> GetLayerTree(
+      scoped_refptr<cc::Layer> content_root_layer) OVERRIDE;
+
+ private:
+  scoped_refptr<cc::Layer> root_layer_;
+
+  DISALLOW_COPY_AND_ASSIGN(LayerTreeBuildHelperImpl);
+};
+
+}
+
+#endif  // CONTENT_BROWSER_ANDROID_LAYER_TREE_BUILD_HELPER_IMPL_H_