Don't scale mask image for new tab button.

ui/gfx/image/image_skia_operations.cc

 // 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 "ui/gfx/image/image_skia_operations.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "skia/ext/image_operations.h"
 #include "ui/base/layout.h"
@@ skipping 149 matching lines @@
         alpha_(alpha) {
   }
 
   virtual ~MaskedImageSource() {
   }
 
   // gfx::ImageSkiaSource overrides:
   virtual ImageSkiaRep GetImageForScale(ui::ScaleFactor scale_factor) OVERRIDE {
     ImageSkiaRep rgb_rep = rgb_.GetRepresentation(scale_factor);
     ImageSkiaRep alpha_rep = alpha_.GetRepresentation(scale_factor);
-    MatchScale(&rgb_rep, &alpha_rep);
     return ImageSkiaRep(SkBitmapOperations::CreateMaskedBitmap(
         rgb_rep.sk_bitmap(), alpha_rep.sk_bitmap()),
                         rgb_rep.scale_factor());
   }
 
  private:
   const ImageSkia rgb_;
   const ImageSkia alpha_;
 
   DISALLOW_COPY_AND_ASSIGN(MaskedImageSource);
@@ skipping 315 matching lines @@
       const ImageSkia& source,
       SkBitmapOperations::RotationAmount rotation) {
   return ImageSkia(new RotatedSource(source, rotation),
       SkBitmapOperations::ROTATION_180_CW == rotation ?
           source.size() :
           gfx::Size(source.height(), source.width()));
 
 }
 
 }  // namespace gfx