Add two pixel-based compositor unittests.

ui/gfx/compositor/test/test_utils.h

Index: ui/gfx/compositor/test/test_utils.h
diff --git a/ui/gfx/compositor/test_utils.h b/ui/gfx/compositor/test/test_utils.h
similarity index 75%
rename from ui/gfx/compositor/test_utils.h
rename to ui/gfx/compositor/test/test_utils.h
index 9c4411ccfe19de05b176e8ffef17909b89fa7716..61a8d41c08d63c776a7e7a0dc315c74ff2503b85 100644
--- a/ui/gfx/compositor/test_utils.h
+++ b/ui/gfx/compositor/test/test_utils.h
@@ -2,8 +2,8 @@
 // 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_UTILS_H_
-#define UI_GFX_COMPOSITOR_TEST_UTILS_H_
+#ifndef UI_GFX_COMPOSITOR_TEST_TEST_UTILS_H_
+#define UI_GFX_COMPOSITOR_TEST_TEST_UTILS_H_
 #pragma once
 
 namespace gfx {
@@ -19,4 +19,4 @@ void CheckApproximatelyEqual(const gfx::Rect& lhs, const gfx::Rect& rhs);
 
 }  // namespace ui
 
-#endif  // UI_GFX_COMPOSITOR_TEST_UTILS_H_
+#endif  // UI_GFX_COMPOSITOR_TEST_TEST_UTILS_H_