Add two pixel-based compositor unittests.

ui/gfx/compositor/compositor_test_support.h

Index: ui/gfx/compositor/compositor_test_support.h
diff --git a/ui/gfx/compositor/compositor_test_support.h b/ui/gfx/compositor/compositor_test_support.h
deleted file mode 100644
index 06a7ee8fda933b5474a718f69c62d53267a874a1..0000000000000000000000000000000000000000
--- a/ui/gfx/compositor/compositor_test_support.h
+++ /dev/null
@@ -1,21 +0,0 @@
-// 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.
-
-#ifndef UI_GFX_COMPOSITOR_TEST_SUPPORT_H_
-#define UI_GFX_COMPOSITOR_TEST_SUPPORT_H_
-#pragma once
-
-namespace ui {
-
-class CompositorTestSupport {
- public:
-  // Called by programs that want to use a real compositor,
-  // but skip the typical initialization of browser_main.cc.
-  static void Initialize();
-  static void Terminate();
-};
-
-}  // namespace ui
-
-#endif  // UI_GFX_COMPOSITOR_TEST_SUPPORT_H_