chrome: Cleanup class/struct forward declarations

chrome/browser/signin/easy_unlock_screenlock_state_handler.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_SIGNIN_EASY_UNLOCK_SCREENLOCK_STATE_HANDLER_H_
 #define CHROME_BROWSER_SIGNIN_EASY_UNLOCK_SCREENLOCK_STATE_HANDLER_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "components/proximity_auth/screenlock_bridge.h"
 #include "components/proximity_auth/screenlock_state.h"
 #include "components/signin/core/account_id/account_id.h"
 
-class PrefService;
-
 // Profile specific class responsible for updating screenlock UI for the user
 // associated with the profile when their Easy Unlock state changes.
 class EasyUnlockScreenlockStateHandler
     : public proximity_auth::ScreenlockBridge::Observer {
  public:
   // Hard lock states.
   enum HardlockState {
     NO_HARDLOCK = 0,           // Hard lock is not enforced. This is default.
     USER_HARDLOCK = 1 << 0,    // Hard lock is requested by user.
     PAIRING_CHANGED = 1 << 1,  // Hard lock because pairing data is changed.
@@ skipping 80 matching lines @@
   // run should be set if the screen was locked by the Easy Unlock setup app.
   bool is_trial_run_ = false;
 
   // Whether the user's phone was ever locked while on the current lock screen.
   bool did_see_locked_phone_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(EasyUnlockScreenlockStateHandler);
 };
 
 #endif  // CHROME_BROWSER_SIGNIN_EASY_UNLOCK_SCREENLOCK_STATE_HANDLER_H_