Revert 141206 - NSImageRep can have a size which is not it's pixel size.

ui/gfx/image/image_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.
 
 #import <AppKit/AppKit.h>
 #import <vector>
 
 #include "base/memory/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
 #include "skia/ext/skia_utils_mac.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/gfx/image/image_skia.h"
 
 namespace gfx {
 namespace internal {
 
 gfx::ImageSkia NSImageToImageSkia(NSImage* image) {
   gfx::ImageSkia image_skia;
   for (NSImageRep* imageRep in [image representations]) {
-    NSSize imageRepSize =
-        NSMakeSize([imageRep pixelsWide], [imageRep pixelsHigh]);
+    NSSize imageRepSize = [imageRep size];
     SkBitmap bitmap(gfx::NSImageRepToSkBitmap(imageRep, imageRepSize, false));
     if (!bitmap.isNull() && !bitmap.empty()) {
       float scaleFactor = imageRepSize.width / [image size].width;
       image_skia.AddBitmapForScale(bitmap, scaleFactor);
     }
   }
   return image_skia;
 }
 
 NSImage* ImageSkiaToNSImage(const gfx::ImageSkia* image_skia) {
   if (image_skia->empty())
     return nil;
 
   scoped_nsobject<NSImage> image([[NSImage alloc] init]);
 
   const std::vector<SkBitmap> bitmaps = image_skia->bitmaps();
   for (std::vector<SkBitmap>::const_iterator it = bitmaps.begin();
        it != bitmaps.end(); ++it) {
     [image addRepresentation:gfx::SkBitmapToNSBitmapImageRep(*it)];
   }
 
   [image setSize:NSMakeSize(image_skia->width(), image_skia->height())];
   return [image.release() autorelease];
 }
 
 }  // namespace internal
 }  // namespace gfx