Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/chromeos/input_method/browser_state_monitor.cc

Index: chrome/browser/chromeos/input_method/browser_state_monitor.cc
diff --git a/chrome/browser/chromeos/input_method/browser_state_monitor.cc b/chrome/browser/chromeos/input_method/browser_state_monitor.cc
index 3de50d30b3ae84e50385a616d97fb9fd6421a901..0b2a8a273b01f4b9a62440b13d313fb8669bb230 100644
--- a/chrome/browser/chromeos/input_method/browser_state_monitor.cc
+++ b/chrome/browser/chromeos/input_method/browser_state_monitor.cc
@@ -153,9 +153,6 @@ void BrowserStateMonitor::Observe(
                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;