NOT FOR REVIEW: Aura on Android

ui/gfx/skbitmap_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/skbitmap_operations.h"
 
 #include <string.h>
 #include <algorithm>
 
 #include "base/logging.h"
@@ skipping 101 matching lines @@
   for (int y = 0; y < masked.height(); ++y) {
     uint32* rgb_row = rgb.getAddr32(0, y);
     uint32* alpha_row = alpha.getAddr32(0, y);
     uint32* dst_row = masked.getAddr32(0, y);
 
     for (int x = 0; x < masked.width(); ++x) {
       SkColor rgb_pixel = SkUnPreMultiply::PMColorToColor(rgb_row[x]);
       SkColor alpha_pixel = SkUnPreMultiply::PMColorToColor(alpha_row[x]);
       int alpha = SkAlphaMul(SkColorGetA(rgb_pixel),
                              SkAlpha255To256(SkColorGetA(alpha_pixel)));
-      int alpha_256 = SkAlpha255To256(alpha);
-      dst_row[x] = SkColorSetARGB(alpha,
-                                  SkAlphaMul(SkColorGetR(rgb_pixel), alpha_256),
-                                  SkAlphaMul(SkColorGetG(rgb_pixel), alpha_256),
-                                  SkAlphaMul(SkColorGetB(rgb_pixel),
-                                             alpha_256));
+      dst_row[x] = SkPreMultiplyARGB(alpha,
+                                     SkColorGetR(rgb_pixel),
+                                     SkColorGetG(rgb_pixel),
+                                     SkColorGetB(rgb_pixel));
     }
   }
 
   return masked;
 }
 
 // static
 SkBitmap SkBitmapOperations::CreateButtonBackground(SkColor color,
                                                     const SkBitmap& image,
                                                     const SkBitmap& mask) {
@@ skipping 650 matching lines @@
   canvas.translate(SkFloatToScalar(result.width() * 0.5f),
                    SkFloatToScalar(result.height() * 0.5f));
   canvas.rotate(angle);
   canvas.translate(-SkFloatToScalar(source.width() * 0.5f),
                    -SkFloatToScalar(source.height() * 0.5f));
   canvas.drawBitmap(source, 0, 0);
   canvas.flush();
 
   return result;
 }