Migrate Obsolete NotificationsSettings and remove content_settings::NotificationsProvider.

chrome/browser/prefs/browser_prefs.cc

Index: chrome/browser/prefs/browser_prefs.cc
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index 3307aa11654bd9bfda0cc9bacc371a48863afdf1..5b3789fc91119fe469e3d65bdc74d6294bb610a4 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -163,7 +163,6 @@ void RegisterUserPrefs(PrefService* user_prefs) {
   PinnedTabCodec::RegisterUserPrefs(user_prefs);
   ExtensionPrefs::RegisterUserPrefs(user_prefs);
   TranslatePrefs::RegisterUserPrefs(user_prefs);
-  DesktopNotificationService::RegisterUserPrefs(user_prefs);
   PrefProxyConfigService::RegisterPrefs(user_prefs);
 #if defined(TOOLKIT_VIEWS)
   BrowserActionsContainer::RegisterUserPrefs(user_prefs);