Revert r150228 "Add support for PNG representation in gfx::Image"

ui/gfx/image/image_unittest_util.h

Index: ui/gfx/image/image_unittest_util.h
diff --git a/ui/gfx/image/image_unittest_util.h b/ui/gfx/image/image_unittest_util.h
index 363ee33f0dc288eec4d15f1dc7cdc07392ba95d2..cab3c5a27ed683f025ae0bd698725a920cf89156 100644
--- a/ui/gfx/image/image_unittest_util.h
+++ b/ui/gfx/image/image_unittest_util.h
@@ -9,7 +9,6 @@
 #define UI_GFX_IMAGE_IMAGE_UNITTEST_UTIL_H_
 
 #include "ui/gfx/image/image.h"
-#include "third_party/skia/include/core/SkColor.h"
 
 namespace gfx {
 namespace test {
@@ -41,10 +40,6 @@ PlatformImage CreatePlatformImage();
 gfx::Image::RepresentationType GetPlatformRepresentationType();
 
 PlatformImage ToPlatformType(const gfx::Image& image);
-PlatformImage CopyPlatformType(const gfx::Image& image);
-
-SkColor GetPlatformImageColor(PlatformImage image);
-void CheckColor(SkColor color, bool is_red);
 
 bool IsPlatformImageValid(PlatformImage image);