Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/extensions/extension_service.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/extensions/extension_service.h"
 
 #include <algorithm>
 #include <set>
 
 #include "base/basictypes.h"
@@ skipping 2564 matching lines @@
           break;
 
       process_map_.RemoveAllFromProcess(process->GetID());
       BrowserThread::PostTask(
           BrowserThread::IO, FROM_HERE,
           base::Bind(&ExtensionInfoMap::UnregisterAllExtensionsInProcess,
                      system_->info_map(),
                      process->GetID()));
       break;
     }
-    case chrome::NOTIFICATION_PREF_CHANGED: {
-      const std::string& pref_name =
-          *content::Details<std::string>(details).ptr();
-      DCHECK(pref_name == prefs::kExtensionInstallAllowList ||
-             pref_name == prefs::kExtensionInstallDenyList)
-          << "Unexpected preference name " << pref_name;
-      IdentifyAlertableExtensions();
-      CheckManagementPolicy();
-      break;
-    }
     case chrome::NOTIFICATION_IMPORT_FINISHED: {
       InitAfterImport();
       break;
     }
 
     default:
       NOTREACHED() << "Unexpected notification type.";
   }
 }
 
+void ExtensionService::OnPreferenceChanged(PrefServiceBase* service,
+                                           const std::string& pref_name) {
+  DCHECK(pref_name == prefs::kExtensionInstallAllowList ||
+         pref_name == prefs::kExtensionInstallDenyList)
+      << "Unexpected preference name " << pref_name;
+  IdentifyAlertableExtensions();
+  CheckManagementPolicy();
+}
+
 bool ExtensionService::HasApps() const {
   return !GetAppIds().empty();
 }
 
 ExtensionIdSet ExtensionService::GetAppIds() const {
   ExtensionIdSet result;
   for (ExtensionSet::const_iterator it = extensions_.begin();
        it != extensions_.end(); ++it) {
     if ((*it)->is_app() && (*it)->location() != Extension::COMPONENT)
       result.insert((*it)->id());
@@ skipping 210 matching lines @@
     // External extensions are initially disabled. We prompt the user before
     // enabling them.
     if (Extension::IsExternalLocation(extension->location()) &&
         !extension_prefs_->IsExternalExtensionAcknowledged(extension->id())) {
       return false;
     }
   }
 
   return true;
 }