components: Cleanup class/struct fwd declarations

components/update_client/update_checker.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 COMPONENTS_UPDATE_CLIENT_UPDATE_CHECKER_H_
 #define COMPONENTS_UPDATE_CLIENT_UPDATE_CHECKER_H_
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "components/update_client/crx_update_item.h"
 #include "components/update_client/update_response.h"
 #include "url/gurl.h"
 
-class GURL;
-
 namespace update_client {
 
 class PersistedData;
 class Configurator;
 
 class UpdateChecker {
  public:
   using UpdateCheckCallback =
       base::Callback<void(int error,
                           const UpdateResponse::Results& results,
@@ skipping 21 matching lines @@
  protected:
   UpdateChecker() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(UpdateChecker);
 };
 
 }  // namespace update_client
 
 #endif  // COMPONENTS_UPDATE_CLIENT_UPDATE_CHECKER_H_