Use a mocked compositor for unit tests

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 {
 
 class TestCompositorDelegate : public ui::CompositorDelegate {
  public:
   TestCompositorDelegate() {}
   virtual ~TestCompositorDelegate() {}
 
   virtual void ScheduleDraw() OVERRIDE {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TestCompositorDelegate);
 };
 
-TestCompositor::TestCompositor()
-    : Compositor(new TestCompositorDelegate, gfx::Size(100, 100)) {
-  owned_delegate_.reset(static_cast<TestCompositorDelegate*>(delegate()));
+TestCompositor::TestCompositor(CompositorDelegate *owner)
+    : Compositor((owner ? owner : new TestCompositorDelegate),
+                 gfx::Size(100, 100)) {
+  if (!owner)
+    owned_delegate_.reset(static_cast<TestCompositorDelegate*>(delegate()));
 }
 
 TestCompositor::~TestCompositor() {
 }
 
 ui::Texture* TestCompositor::CreateTexture() {
   return new TestTexture();
 }
 
 void TestCompositor::OnNotifyStart(bool clear) {
 }
 
 void TestCompositor::OnNotifyEnd() {
 }
 
 void TestCompositor::Blur(const gfx::Rect& bounds) {
 }
 
 void TestCompositor::OnWidgetSizeChanged() {
 }
 
 }  // namespace ui