Remove unused NetPrefObserver forward declaration.

chrome/browser/profiles/profile_impl.h

 // Copyright (c) 2012 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.
 
 // This class gathers state related to a single user profile.
 
 #ifndef CHROME_BROWSER_PROFILES_PROFILE_IMPL_H_
 #define CHROME_BROWSER_PROFILES_PROFILE_IMPL_H_
 
 #include <memory>
 #include <string>
 
 #include "base/files/file_path.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/timer/timer.h"
 #include "build/build_config.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_impl_io_data.h"
 #include "chrome/browser/ui/zoom/chrome_zoom_level_prefs.h"
 #include "components/prefs/pref_change_registrar.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/host_zoom_map.h"
 
-class NetPrefObserver;
 class PrefService;
 
 class TrackedPreferenceValidationDelegate;
 
 #if defined(OS_CHROMEOS)
 namespace chromeos {
 class KioskTest;
 class LocaleChangeGuard;
 class Preferences;
 class SupervisedUserTestBase;
@@ skipping 232 matching lines @@
   // components/keyed_service/content/browser_context_keyed_service_factory.*
 
   Profile::Delegate* delegate_;
 
   chrome_browser_net::Predictor* predictor_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileImpl);
 };
 
 #endif  // CHROME_BROWSER_PROFILES_PROFILE_IMPL_H_