Add support for multi resolution icons

ui/gfx/image_mac.mm

Index: ui/gfx/image_mac.mm
diff --git a/ui/gfx/image_mac.mm b/ui/gfx/image_mac.mm
index b3dc9776ebf135835754539f38873801a45368c4..544c214ec843f53898cf5254c4057dd51bcaff7e 100644
--- a/ui/gfx/image_mac.mm
+++ b/ui/gfx/image_mac.mm
@@ -4,14 +4,22 @@
 
 #import <AppKit/AppKit.h>
 
+#include "base/memory/scoped_ptr.h"
 #include "skia/ext/skia_utils_mac.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
 namespace gfx {
 namespace internal {
 
-const SkBitmap* NSImageToSkBitmap(NSImage* image) {
-  return new SkBitmap(::gfx::NSImageToSkBitmap(image, [image size], false));
+bool NSImageToSkBitmaps(NSImage* image, std::vector<const SkBitmap*>& bitmaps) {
+  for (NSImageRep* imageRep in [image representations]) {
+    scoped_ptr<SkBitmap> bitmap(new SkBitmap(
+        gfx::NSImageRepToSkBitmap(imageRep, [imageRep size], false)));
+    if (bitmap->isNull())
+      return false;
+    bitmaps.push_back(bitmap.release());
+  }
+  return true;
 }
 
 }  // namespace internal