Add support for multi resolution icons

chrome/browser/themes/theme_service_mac.mm

Index: chrome/browser/themes/theme_service_mac.mm
diff --git a/chrome/browser/themes/theme_service_mac.mm b/chrome/browser/themes/theme_service_mac.mm
index 30d359ee203040d8f36aca70ad7887d964e97253..c355e0d4155ac572b6c5a4a3c9d84d03234d010d 100644
--- a/chrome/browser/themes/theme_service_mac.mm
+++ b/chrome/browser/themes/theme_service_mac.mm
@@ -10,7 +10,9 @@
 #include "chrome/browser/themes/browser_theme_pack.h"
 #include "skia/ext/skia_utils_mac.h"
 #import "third_party/GTM/AppKit/GTMNSColor+Luminance.h"
+#include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/color_utils.h"
+#include "ui/gfx/image.h"
 
 NSString* const kBrowserThemeDidChangeNotification =
     @"BrowserThemeDidChangeNotification";
@@ -44,8 +46,16 @@ NSImage* ThemeService::GetNSImageNamed(int id, bool allow_default) const {
   // SkBitmap > native conversion?
   // - For consistency with other platforms.
   // - To get the generated tinted images.
-  SkBitmap* bitmap = GetBitmapNamed(id);
-  NSImage* nsimage = gfx::SkBitmapToNSImage(*bitmap);
+  NSImage* nsimage = nil;
+  if (theme_pack_.get()) {
+    SkBitmap* bitmap = theme_pack_->GetBitmapNamed(id);
+    if (bitmap)
+      nsimage = gfx::SkBitmapToNSImage(*bitmap);
+  }
+
+  if (!nsimage) {
+    nsimage = rb_.GetNativeImageNamed(id);
+  }
 
   // We loaded successfully.  Cache the image.
   if (nsimage) {