Use WebKit compositor in ui::Layer

ui/gfx/compositor/test_compositor.cc

 // Copyright (c) 2011 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.
 
 #include "ui/gfx/compositor/test_compositor.h"
 
 #include "ui/gfx/compositor/test_texture.h"
 
 namespace ui {
 
@@ skipping 22 matching lines @@
 
 void TestCompositor::OnNotifyStart(bool clear) {
 }
 
 void TestCompositor::OnNotifyEnd() {
 }
 
 void TestCompositor::Blur(const gfx::Rect& bounds) {
 }
 
+void TestCompositor::DrawTree() {
+#if !defined(USE_WEBKIT_COMPOSITOR)
+  Compositor::DrawTree();
+#endif
+}
+
 void TestCompositor::OnWidgetSizeChanged() {
 }
 
 }  // namespace ui