chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/login/users/avatar/user_image_manager_test_util.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_CHROMEOS_LOGIN_USERS_AVATAR_USER_IMAGE_MANAGER_TEST_UTIL_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_USERS_AVATAR_USER_IMAGE_MANAGER_TEST_UTIL_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/run_loop.h"
 #include "chrome/browser/image_decoder.h"
 
-class SKBitmap;
-
 namespace base {
 class FilePath;
 }
 
 namespace gfx {
 class ImageSkia;
 }
 
 namespace chromeos {
 namespace test {
@@ skipping 21 matching lines @@
 
   std::unique_ptr<gfx::ImageSkia> decoded_image_;
 
   DISALLOW_COPY_AND_ASSIGN(ImageLoader);
 };
 
 }  // namespace test
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_USERS_AVATAR_USER_IMAGE_MANAGER_TEST_UTIL_H_