chrome: Cleanup class/struct forward declarations

chrome/browser/sync/test/integration/password_manager_setting_migrator_helper.h

 // Copyright (c) 2015 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_SYNC_TEST_INTEGRATION_PASSWORD_MANAGER_SETTING_MIGRATOR_HELPER_H_
 #define CHROME_BROWSER_SYNC_TEST_INTEGRATION_PASSWORD_MANAGER_SETTING_MIGRATOR_HELPER_H_
 
-namespace base {
-class FieldTrial;
-}
-
 class Profile;
 
 namespace password_manager_setting_migrater_helper {
 
 // Ensures that the password manager setting migration field trial experiment is
 // enabled. Returns false if it already was enabled, and true if it got enabled
 // during this call.
 bool EnsureFieldTrialSetup();
 
 // Triggers Initalization of the PasswordManagerSettingMigrator service.
 // The service registers observes which are required in order to perform
 // migration.
 void InitializePreferencesMigration(Profile* profile);
 
 // Checks that on the client number |index| the value for
 // kCredentialsEnableService is equal to |new_pref_value| and the value for
 // kPasswordManagerSavingEnabled is equal to |old_pref_value|.
 void ExpectPrefValuesOnClient(int index,
                               bool new_pref_value,
                               bool old_pref_value);
 
 }  // namespace password_manager_setting_migrater_helper
 
 #endif  // CHROME_BROWSER_SYNC_TEST_INTEGRATION_PASSWORD_MANAGER_SETTING_MIGRATOR_HELPER_H_