chrome: Cleanup class/struct forward declarations

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/files/file_path.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "content/public/browser/url_data_source.h"
 
 namespace base {
 class SequencedTaskRunner;
 }
 
-// TODO(michaelpg): Remove dependency on user_manager.
-namespace user_manager {
-class UserImage;
-}
-
 namespace chromeos {
 
 // Data source that reads and decodes an image from the RO file system.
 class ImageSource : public content::URLDataSource {
  public:
   ImageSource();
   ~ImageSource() override;
 
   // content::URLDataSource implementation.
   std::string GetSource() const override;
@@ skipping 19 matching lines @@
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
 
   base::WeakPtrFactory<ImageSource> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageSource);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_CHROMEOS_IMAGE_SOURCE_H_