Fix alpha pre-multiplication error with custom cursor images

content/common/cursors/webcursor.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 "content/common/cursors/webcursor.h"
 
 #include "base/logging.h"
 #include "base/pickle.h"
 #include "third_party/WebKit/public/platform/WebImage.h"
 
@@ skipping 213 matching lines @@
   custom_scale_ = other.custom_scale_;
   custom_data_ = other.custom_data_;
   CopyPlatformData(other);
 }
 
 void WebCursor::SetCustomData(const SkBitmap& bitmap) {
   if (bitmap.empty())
     return;
 
   // Fill custom_data_ directly with the NativeImage pixels.
-  SkAutoLockPixels bitmap_lock(bitmap);
   custom_data_.resize(bitmap.getSize());
-  if (!custom_data_.empty())
-    memcpy(&custom_data_[0], bitmap.getPixels(), bitmap.getSize());
+  if (!custom_data_.empty()) {
+    //This will divide color values by alpha (un-premultiply) if necessary
+    SkImageInfo dstInfo = bitmap.info().makeAlphaType(kUnpremul_SkAlphaType);
+    bitmap.readPixels(dstInfo, &custom_data_[0], dstInfo.minRowBytes(), 0, 0);
+  }
   custom_size_.set_width(bitmap.width());
   custom_size_.set_height(bitmap.height());
 }
 
 void WebCursor::ImageFromCustomData(SkBitmap* image) const {
   if (custom_data_.empty())
     return;
 
-  if (!image->tryAllocN32Pixels(custom_size_.width(), custom_size_.height()))
+  SkImageInfo image_info = SkImageInfo::MakeN32(custom_size_.width(),
+                                                custom_size_.height(),
+                                                kUnpremul_SkAlphaType);
+  if (!image->tryAllocPixels(image_info))
     return;
   memcpy(image->getPixels(), &custom_data_[0], custom_data_.size());
 }
 
 void WebCursor::ClampHotspot() {
   if (!IsCustom())
     return;
 
   // Clamp the hotspot to the custom image's dimensions.
   hotspot_.set_x(std::max(0,
                           std::min(custom_size_.width() - 1, hotspot_.x())));
   hotspot_.set_y(std::max(0,
                           std::min(custom_size_.height() - 1, hotspot_.y())));
 }
 
 }  // namespace content