[cros] Add user image transparency support.

BUG=chromium-os:23281
TEST=Manual: see bug description

Review URL: http://codereview.chromium.org/8923004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@114045 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/login/user_manager.cc

@@ -770,7 +770,7 @@ void UserManager::SaveImageToFile(const std::string& username,
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 
   std::vector<unsigned char> encoded_image;
-  if (!gfx::PNGCodec::EncodeBGRASkBitmap(image, true, &encoded_image)) {
+  if (!gfx::PNGCodec::EncodeBGRASkBitmap(image, false, &encoded_image)) {
     LOG(ERROR) << "Failed to PNG encode the image.";
     return;
   }