Load 2x resources on demand

chrome/browser/icon_loader_mac.mm

 // 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 "chrome/browser/icon_loader.h"
 
 #import <AppKit/AppKit.h>
 
 #include "base/bind.h"
 #include "base/message_loop.h"
@@ skipping 15 matching lines @@
     switch (icon_size_) {
       case IconLoader::SMALL:
         size = NSMakeSize(16, 16);
         break;
       case IconLoader::NORMAL:
         size = NSMakeSize(32, 32);
         break;
       default:
         NOTREACHED();
     }
-    image_.reset(new gfx::Image(gfx::ImageSkiaFromResizedNSImage(icon, size)));
+    gfx::ImageSkia image_skia(gfx::ImageSkiaFromResizedNSImage(icon, size));
+    image_skia.MakeThreadSafe();
+    image_.reset(new gfx::Image(image_skia));
   }
 
   target_message_loop_->PostTask(FROM_HERE,
       base::Bind(&IconLoader::NotifyDelegate, this));
 }