chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/net/network_throttling_observer.h

 // Copyright 2016 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_NET_NETWORK_THROTTLING_OBSERVER_H_
 #define CHROME_BROWSER_CHROMEOS_NET_NETWORK_THROTTLING_OBSERVER_H_
 
 #include <string>
 
 #include "base/memory/weak_ptr.h"
 #include "components/prefs/pref_change_registrar.h"
 
 class PrefRegistrySimple;
-class Profile;
 
 namespace chromeos {
 
 // NetworkThrottlingObserver is a singleton, owned by
 // ChromeBrowserMainPartsChromeos.
 // This class is responsible for propagating network bandwidth throttling policy
 // changes (prefs::kNetworkThrottlingEnabled) in Chrome down to Shill which
 // implements by calling 'tc' in the kernel.
 class NetworkThrottlingObserver {
  public:
   explicit NetworkThrottlingObserver(PrefService* local_state);
   ~NetworkThrottlingObserver();
 
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
  private:
   // Callback used when prefs::kNetworkThrottlingEnabled changes
   void OnPreferenceChanged(const std::string& pref_name);
 
   PrefService* local_state_;
   PrefChangeRegistrar pref_change_registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkThrottlingObserver);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_NET_NETWORK_THROTTLING_OBSERVER_H_