Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/signin/signin_manager.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/signin/signin_manager.h"
 
 #include <string>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 479 matching lines @@
 void SigninManager::OnGetUserInfoFailure(const GoogleServiceAuthError& error) {
   LOG(ERROR) << "Unable to retreive the canonical email address. Login failed.";
   // REVIEW: why does this call OnClientLoginFailure?
   OnClientLoginFailure(error);
 }
 
 void SigninManager::Observe(int type,
                             const content::NotificationSource& source,
                             const content::NotificationDetails& details) {
   switch (type) {
-    case chrome::NOTIFICATION_PREF_CHANGED:
-      DCHECK(*content::Details<std::string>(details).ptr() ==
-             prefs::kGoogleServicesUsernamePattern);
-      if (!authenticated_username_.empty() &&
-          !IsAllowedUsername(authenticated_username_)) {
-        // Signed in user is invalid according to the current policy so sign
-        // the user out.
-        SignOut();
-      }
-      break;
-
 #if !defined(OS_CHROMEOS)
     case chrome::NOTIFICATION_TOKEN_AVAILABLE: {
       TokenService::TokenAvailableDetails* tok_details =
           content::Details<TokenService::TokenAvailableDetails>(
               details).ptr();
 
       // If a GAIA service token has become available, use it to pre-login the
       // user to other services that depend on GAIA credentials.
       if (tok_details->service() == GaiaConstants::kGaiaService) {
         if (client_login_.get() == NULL) {
           client_login_.reset(
               new GaiaAuthFetcher(this,
                                   GaiaConstants::kChromeSource,
                                   profile_->GetRequestContext()));
         }
 
         client_login_->StartMergeSession(tok_details->token());
 
         // We only want to do this once per sign-in.
         CleanupNotificationRegistration();
       }
       break;
     }
 #endif
     default:
       NOTREACHED();
   }
 }
 
+void SigninManager::OnPreferenceChanged(PrefServiceBase* service,
+                                        const std::string& pref_name) {
+  DCHECK_EQ(prefs::kGoogleServicesUsernamePattern, pref_name);
+  if (!authenticated_username_.empty() &&
+      !IsAllowedUsername(authenticated_username_)) {
+    // Signed in user is invalid according to the current policy so sign
+    // the user out.
+    SignOut();
+  }
+}