chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/api/enterprise_platform_keys_private/enterprise_platform_keys_private_api.h

 // 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.
 
 // TODO(dkrahn): Clean up this private API once all clients have been migrated
 // to use the public API. crbug.com/588339.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_ENTERPRISE_PLATFORM_KEYS_PRIVATE_ENTERPRISE_PLATFORM_KEYS_PRIVATE_API_H__
 #define CHROME_BROWSER_EXTENSIONS_API_ENTERPRISE_PLATFORM_KEYS_PRIVATE_ENTERPRISE_PLATFORM_KEYS_PRIVATE_API_H__
 
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "chrome/common/extensions/api/enterprise_platform_keys_private.h"
 #include "chromeos/attestation/attestation_constants.h"
 #include "chromeos/attestation/attestation_flow.h"
 #include "chromeos/dbus/cryptohome_client.h"
 #include "chromeos/dbus/dbus_method_call_status.h"
 #include "components/signin/core/account_id/account_id.h"
 #include "extensions/browser/extension_function.h"
 #include "third_party/cros_system_api/dbus/service_constants.h"
 
-class PrefService;
 class Profile;
 
 namespace chromeos {
 class CryptohomeClient;
 class InstallAttributes;
 }
 
 namespace cryptohome {
 class AsyncMethodCaller;
 }
@@ skipping 252 matching lines @@
   EPKPChallengeUserKey* impl_;
 
   DECLARE_EXTENSION_FUNCTION(
       "enterprise.platformKeysPrivate.challengeUserKey",
       ENTERPRISE_PLATFORMKEYSPRIVATE_CHALLENGEUSERKEY);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_ENTERPRISE_PLATFORM_KEYS_PRIVATE_ENTERPRISE_PLATFORM_KEYS_PRIVATE_API_H__