Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/extensions/api/preference/preference_api.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/api/preference/preference_api.h"
 
 #include <map>
 #include <utility>
 
 #include "base/memory/singleton.h"
@@ skipping 235 matching lines @@
   registrar_.Init(profile_->GetPrefs());
   incognito_registrar_.Init(profile_->GetOffTheRecordPrefs());
   for (size_t i = 0; i < arraysize(kPrefMapping); ++i) {
     registrar_.Add(kPrefMapping[i].browser_pref, this);
     incognito_registrar_.Add(kPrefMapping[i].browser_pref, this);
   }
 }
 
 PreferenceEventRouter::~PreferenceEventRouter() { }
 
-void PreferenceEventRouter::Observe(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
-  DCHECK_EQ(chrome::NOTIFICATION_PREF_CHANGED, type);
-  OnPrefChanged(content::Source<PrefService>(source).ptr(),
-                *content::Details<const std::string>(details).ptr());
+void PreferenceEventRouter::OnPreferenceChanged(PrefServiceBase* service,
+                                                const std::string& pref_name) {
+  OnPrefChanged(service, pref_name);
 }
 
-void PreferenceEventRouter::OnPrefChanged(PrefService* pref_service,
+void PreferenceEventRouter::OnPrefChanged(PrefServiceBase* pref_service,
                                           const std::string& browser_pref) {
   bool incognito = (pref_service != profile_->GetPrefs());
 
   std::string event_name;
   APIPermission::ID permission = APIPermission::kInvalid;
   bool rv = PrefMapping::GetInstance()->FindEventForBrowserPref(
       browser_pref, &event_name, &permission);
   DCHECK(rv);
 
   ListValue args;
   DictionaryValue* dict = new DictionaryValue();
   args.Append(dict);
-  const PrefService::Preference* pref =
+  const PrefServiceBase::Preference* pref =
       pref_service->FindPreference(browser_pref.c_str());
   CHECK(pref);
   ExtensionService* extension_service = profile_->GetExtensionService();
   PrefTransformerInterface* transformer =
       PrefMapping::GetInstance()->FindTransformerForBrowserPref(browser_pref);
   Value* transformed_value =
       transformer->BrowserToExtensionPref(pref->GetValue());
   if (!transformed_value) {
     LOG(ERROR) <<
         ExtensionErrorUtils::FormatErrorMessage(kConversionErrorMessage,
@@ skipping 221 matching lines @@
   if (!ValidateBrowserPref(pref_key, &browser_pref))
     return false;
 
   extensions::ExtensionPrefs* prefs =
       profile_->GetExtensionService()->extension_prefs();
   prefs->RemoveExtensionControlledPref(extension_id(), browser_pref, scope);
   return true;
 }
 
 }  // namespace extensions