Windows: Fix opacity of drag images....

gfx/skbitmap_operations.h

 // Copyright (c) 2009 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.
 
 #ifndef GFX_SKBITMAP_OPERATIONS_H_
 #define GFX_SKBITMAP_OPERATIONS_H_
 
 #include "gfx/color_utils.h"
 #include "testing/gtest/include/gtest/gtest_prod.h"
 
@@ skipping 64 matching lines @@
   // the final size, and then use traditional resampling on the result.
   // Because the bitmap will be closer to the final size, it will be faster,
   // and linear interpolation will generally work well as a second step.
   static SkBitmap DownsampleByTwoUntilSize(const SkBitmap& bitmap,
                                            int min_w, int min_h);
 
   // Makes a bitmap half has large in each direction by averaging groups of
   // 4 pixels. This is one step in generating a mipmap.
   static SkBitmap DownsampleByTwo(const SkBitmap& bitmap);
 
+  // Unpremultiplies all pixels in |bitmap|. You almost never want to call
+  // this, as |SkBitmap|s are always premultiplied by conversion. Call this
+  // only if you will pass the bitmap's data into a system function that
+  // doesn't expect premultiplied colors.
+  static SkBitmap UnPreMultiply(const SkBitmap& bitmap);
+
  private:
   SkBitmapOperations();  // Class for scoping only.
 
   FRIEND_TEST(SkBitmapOperationsTest, DownsampleByTwo);
   FRIEND_TEST(SkBitmapOperationsTest, DownsampleByTwoSmall);
 };
 
 #endif  // GFX_SKBITMAP_OPERATIONS_H_