Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/extensions/component_loader.cc

Index: chrome/browser/extensions/component_loader.cc
diff --git a/chrome/browser/extensions/component_loader.cc b/chrome/browser/extensions/component_loader.cc
index 59b2bb77a2efdf82d7df1100e534556d1eedff60..529c0605d5823fedf8f1bc459196ef382c55771d 100644
--- a/chrome/browser/extensions/component_loader.cc
+++ b/chrome/browser/extensions/component_loader.cc
@@ -407,20 +407,12 @@ void ComponentLoader::AddDefaultComponentExtensions() {
   AddScriptBubble();
 }
 
-void ComponentLoader::Observe(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
-  if (type == chrome::NOTIFICATION_PREF_CHANGED) {
-    const std::string* name =
-        content::Details<const std::string>(details).ptr();
-    if (*name == prefs::kEnterpriseWebStoreURL)
-      AddOrReloadEnterpriseWebStore();
-    else
-      NOTREACHED();
-  } else {
+void ComponentLoader::OnPreferenceChanged(PrefServiceBase* service,
+                                          const std::string& pref_name) {
+  if (pref_name == prefs::kEnterpriseWebStoreURL)
+    AddOrReloadEnterpriseWebStore();
+  else
     NOTREACHED();
-  }
 }
 
 // static