Add layerTreeBuildHelper to control layer tree in ContentViewRenderView

content/public/browser/android/layer_tree_build_helper.h

Index: content/public/browser/android/layer_tree_build_helper.h
diff --git a/content/public/browser/android/layer_tree_build_helper.h b/content/public/browser/android/layer_tree_build_helper.h
new file mode 100644
index 0000000000000000000000000000000000000000..4f23a4bed12036d7b127e64b48a5f3950672b2bf
--- /dev/null
+++ b/content/public/browser/android/layer_tree_build_helper.h
@@ -0,0 +1,31 @@
+// 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_