Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/content_settings/content_settings_pref_provider.cc

Index: chrome/browser/content_settings/content_settings_pref_provider.cc
diff --git a/chrome/browser/content_settings/content_settings_pref_provider.cc b/chrome/browser/content_settings/content_settings_pref_provider.cc
index 6dfb9ad87a86f2238ae7c4f50ccc56684d7ffdc2..1bf02a1c165b183398ff601290ba9128404ae5d3 100644
--- a/chrome/browser/content_settings/content_settings_pref_provider.cc
+++ b/chrome/browser/content_settings/content_settings_pref_provider.cc
@@ -217,31 +217,24 @@ void PrefProvider::ClearAllContentSettingsRules(
                   std::string());
 }
 
-void PrefProvider::Observe(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
+void PrefProvider::OnPreferenceChanged(PrefServiceBase* service,
+                                       const std::string& name) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  if (type == chrome::NOTIFICATION_PREF_CHANGED) {
-    DCHECK_EQ(prefs_, content::Source<PrefService>(source).ptr());
-    if (updating_preferences_)
-      return;
-
-    std::string* name = content::Details<std::string>(details).ptr();
-    if (*name != prefs::kContentSettingsPatternPairs) {
-      NOTREACHED() << "Unexpected preference observed";
-      return;
-    }
-    ReadContentSettingsFromPref(true);
+  DCHECK_EQ(prefs_, service);
+  if (updating_preferences_)
+    return;
 
-    NotifyObservers(ContentSettingsPattern(),
-                    ContentSettingsPattern(),
-                    CONTENT_SETTINGS_TYPE_DEFAULT,
-                    std::string());
-  } else {
-    NOTREACHED() << "Unexpected notification";
+  if (name != prefs::kContentSettingsPatternPairs) {
+    NOTREACHED() << "Unexpected preference observed";
+    return;
   }
+  ReadContentSettingsFromPref(true);
+
+  NotifyObservers(ContentSettingsPattern(),
+                  ContentSettingsPattern(),
+                  CONTENT_SETTINGS_TYPE_DEFAULT,
+                  std::string());
 }
 
 PrefProvider::~PrefProvider() {