Fix login visual hitch on chromebook

chrome/browser/ui/webui/chromeos/login/user_image_screen_handler.cc

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright (c) 2013 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 "chrome/browser/ui/webui/chromeos/login/user_image_screen_handler.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/values.h"
 #include "chrome/browser/chromeos/camera_detector.h"
 #include "chrome/browser/chromeos/login/default_user_images.h"
 #include "chrome/browser/chromeos/login/user.h"
 #include "chrome/browser/chromeos/login/webui_login_display.h"
 #include "chrome/browser/ui/webui/chromeos/login/oobe_ui.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
+#include "content/public/browser/browser_thread.h"
 #include "googleurl/src/gurl.h"
 #include "grit/generated_resources.h"
 #include "net/base/data_url.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/views/widget/widget.h"
 #include "ui/webui/web_ui_util.h"
 
+using content::BrowserThread;
+
 namespace chromeos {
 
 UserImageScreenHandler::UserImageScreenHandler()
     : screen_(NULL),
       show_on_init_(false),
       selected_image_(User::kInvalidImageIndex),
       accept_photo_after_decoding_(false),
       user_photo_data_url_(chrome::kAboutBlankURL),
       profile_picture_data_url_(chrome::kAboutBlankURL),
       profile_picture_absent_(false),
@@ skipping 146 matching lines @@
   if (selected_image_ != User::kInvalidImageIndex)
     SelectImage(selected_image_);
 
   if (profile_picture_data_url_ != chrome::kAboutBlankURL)
     SendProfileImage(profile_picture_data_url_);
   else if (profile_picture_absent_)
     OnProfileImageAbsent();
 }
 
 void UserImageScreenHandler::HandlePhotoTaken(const base::ListValue* args) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   std::string image_url;
   if (!args || args->GetSize() != 1 || !args->GetString(0, &image_url))
     NOTREACHED();
   DCHECK(!image_url.empty());
 
   std::string mime_type, charset, raw_data;
   if (!net::DataURL::Parse(GURL(image_url), &mime_type, &charset, &raw_data))
     NOTREACHED();
   DCHECK_EQ("image/png", mime_type);
 
   user_photo_ = gfx::ImageSkia();
   user_photo_data_url_ = image_url;
 
   if (image_decoder_.get())
     image_decoder_->set_delegate(NULL);
   image_decoder_ = new ImageDecoder(this, raw_data,
                                     ImageDecoder::DEFAULT_CODEC);
-  image_decoder_->Start();
+  scoped_refptr<base::MessageLoopProxy> task_runner =
+      BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI);
+  image_decoder_->Start(task_runner);
 }
 
 void UserImageScreenHandler::HandleCheckCameraPresence(
     const base::ListValue* args) {
   DCHECK(args->empty());
   CheckCameraPresence();
 }
 
 void UserImageScreenHandler::HandleSelectImage(const base::ListValue* args) {
   std::string image_url;
@@ skipping 66 matching lines @@
   user_photo_ = gfx::ImageSkia::CreateFrom1xBitmap(decoded_image);
   if (screen_ && accept_photo_after_decoding_)
     screen_->OnPhotoTaken(user_photo_);
 }
 
 void UserImageScreenHandler::OnDecodeImageFailed(const ImageDecoder* decoder) {
   NOTREACHED() << "Failed to decode PNG image from WebUI";
 }
 
 }  // namespace chromeos