Fix threading bugs in product label UI.

chrome/browser/ui/webui/chromeos/image_source.h

 // Copyright 2014 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 CHROME_BROWSER_UI_WEBUI_CHROMEOS_IMAGE_SOURCE_H_
 #define CHROME_BROWSER_UI_WEBUI_CHROMEOS_IMAGE_SOURCE_H_
 
 #include <string>
 
 #include "base/macros.h"
@@ skipping 20 matching lines @@
  public:
   ImageSource();
   ~ImageSource() override;
 
   // content::URLDataSource implementation.
   std::string GetSource() const override;
   void StartDataRequest(
       const std::string& path,
       int render_process_id,
       int render_frame_id,
-      const content::URLDataSource::GotDataCallback& callback) override;
+      const content::URLDataSource::GotDataCallback& got_data_callback)
+      override;
+
   std::string GetMimeType(const std::string& path) const override;
 
  private:
-  void StartOnFileThread(
-      const std::string& path,
-      const content::URLDataSource::GotDataCallback& callback);
+  // Callback after attempting to start loading the image.
+  void LoadImageAttempted(
+      const content::URLDataSource::GotDataCallback& got_data_callback,
+      bool load_started);
 
   // Callback for user_manager::UserImageLoader.
   void ImageLoaded(
-    const content::URLDataSource::GotDataCallback& callback,
-    const user_manager::UserImage& user_image) const;
+      const content::URLDataSource::GotDataCallback& got_data_callback,
+      const user_manager::UserImage& user_image) const;
 
   // Checks whether we have allowed the image to be loaded.
   bool IsWhitelisted(const std::string& path) const;
 
   // The background task runner on which file I/O and image decoding are done.
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
 
   scoped_refptr<UserImageLoader> image_loader_;
 
   base::WeakPtrFactory<ImageSource> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageSource);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_CHROMEOS_IMAGE_SOURCE_H_