Use a mocked compositor for unit tests

ui/gfx/compositor/layer_unittest.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 "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/canvas_skia.h"
 #include "ui/gfx/compositor/compositor_observer.h"
@@ skipping 220 matching lines @@
   DrawTree(l1.get());
 }
 
 class LayerWithDelegateTest : public testing::Test {
  public:
   LayerWithDelegateTest() {}
   virtual ~LayerWithDelegateTest() {}
 
   // Overridden from testing::Test:
   virtual void SetUp() OVERRIDE {
-    compositor_ = new TestCompositor();
+    compositor_ = new TestCompositor(NULL);
   }
 
   virtual void TearDown() OVERRIDE {
   }
 
   Compositor* compositor() { return compositor_.get(); }
 
   virtual Layer* CreateLayer(Layer::LayerType type) {
     return new Layer(compositor(), type);
   }
@@ skipping 454 matching lines @@
   EXPECT_FALSE(l2->IsDrawn());
   EXPECT_FALSE(l3->IsDrawn());
 
   l1->SetVisible(true);
   EXPECT_TRUE(l1->IsDrawn());
   EXPECT_TRUE(l2->IsDrawn());
   EXPECT_FALSE(l3->IsDrawn());
 }
 
 } // namespace ui