Enables HiDPI favicon to be displayed in tab strip on CrOS

ui/gfx/image/image_skia_unittest.cc

 // Copyright (c) 2012 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/image/image_skia.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/base/layout.h"
 #include "ui/gfx/image/image_skia_rep.h"
@@ skipping 178 matching lines @@
 }
 
 TEST(ImageSkiaTest, OperatorBitmapFromSource) {
   ImageSkia image_skia(new DynamicSource(Size(100, 200)), Size(100, 200));
   // ImageSkia should use the source to create the bitmap.
   const SkBitmap& bitmap = image_skia;
   ASSERT_NE(static_cast<SkBitmap*>(NULL), &bitmap);
   EXPECT_FALSE(bitmap.isNull());
 }
 
+TEST(ImageSkiaTest, BackedBySameObjectAs) {
+  // Null images should all be backed by the same object (NULL).
+  ImageSkia image;
+  ImageSkia unrelated;
+  EXPECT_TRUE(image.BackedBySameObjectAs(unrelated));
+
+  image.AddRepresentation(gfx::ImageSkiaRep(gfx::Size(10, 10),
+                                            ui::SCALE_FACTOR_100P));
+  ImageSkia copy = image;
+  copy.AddRepresentation(gfx::ImageSkiaRep(gfx::Size(10, 10),
+                                           ui::SCALE_FACTOR_200P));
+  unrelated.AddRepresentation(gfx::ImageSkiaRep(gfx::Size(10, 10),
+                                                ui::SCALE_FACTOR_100P));
+  EXPECT_TRUE(image.BackedBySameObjectAs(copy));
+  EXPECT_FALSE(image.BackedBySameObjectAs(unrelated));
+  EXPECT_FALSE(copy.BackedBySameObjectAs(unrelated));
+}
+
 }  // namespace gfx