Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/chromeos/input_method/browser_state_monitor.cc

 // 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.
 
 #include "chrome/browser/chromeos/input_method/browser_state_monitor.h"
 
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chromeos/input_method/input_method_util.h"
 #include "chrome/browser/chromeos/language_preferences.h"
 #include "chrome/browser/prefs/pref_service.h"
@@ skipping 135 matching lines @@
       DVLOG(1) << "Received chrome::NOTIFICATION_SESSION_STARTED";
       SetState(InputMethodManager::STATE_BROWSER_SCREEN);
       break;
     }
     case chrome::NOTIFICATION_SCREEN_LOCK_STATE_CHANGED: {
       const bool is_screen_locked = *content::Details<bool>(details).ptr();
       SetState(is_screen_locked ? InputMethodManager::STATE_LOCK_SCREEN :
                InputMethodManager::STATE_BROWSER_SCREEN);
       break;
     }
-    case chrome::NOTIFICATION_PREF_CHANGED: {
-      break;  // just ignore the notification.
-    }

[Mattias Nissler (ping if slow), 2012/10/31 13:29:35]

It seems this is entirely dead code. I guess we should check with the OWNERS.

[Jói, 2012/10/31 14:56:26]

It's possible they received this in an inheritance hierarchy via a superclass or
subclass or something.  It's dead though, the NOTIFICATION_PREF_CHANGED doesn't
even exist any more and the code did nothing before this change anyway.

     default: {
       NOTREACHED();
       break;
     }
   }
   // Note: browser notifications are sent in the following order.
   //
   // Normal login:
   // 1. chrome::NOTIFICATION_LOGIN_USER_CHANGED is sent.
   // 2. Preferences::NotifyPrefChanged() is called. preload_engines (which
@@ skipping 16 matching lines @@
 
 void BrowserStateMonitor::SetState(InputMethodManager::State new_state) {
   const InputMethodManager::State old_state = state_;
   state_ = new_state;
   if (old_state != state_)
     manager_->SetState(state_);
 }
 
 }  // namespace input_method
 }  // namespace chromeos