components: Move PrefRegistrySyncable into user_prefs namespace.

chrome/browser/ui/webui/sync_promo/sync_promo_handler.h

Index: chrome/browser/ui/webui/sync_promo/sync_promo_handler.h
diff --git a/chrome/browser/ui/webui/sync_promo/sync_promo_handler.h b/chrome/browser/ui/webui/sync_promo/sync_promo_handler.h
index 0dde9af557915a7f99e0d439a095ab08a894bf98..8f25ab46ae8ec718e24bcc282157d3684697b6cb 100644
--- a/chrome/browser/ui/webui/sync_promo/sync_promo_handler.h
+++ b/chrome/browser/ui/webui/sync_promo/sync_promo_handler.h
@@ -8,7 +8,10 @@
 #include "chrome/browser/ui/webui/sync_setup_handler.h"
 
 class PrefService;
+
+namespace user_prefs {
 class PrefRegistrySyncable;
+}
 
 // The handler for JavaScript messages related to the "sync promo" page.
 class SyncPromoHandler : public SyncSetupHandler {
@@ -18,7 +21,7 @@ class SyncPromoHandler : public SyncSetupHandler {
 
   // Called to register our preferences before we use them (so there will be a
   // default if not present yet).
-  static void RegisterUserPrefs(PrefRegistrySyncable* registry);
+  static void RegisterUserPrefs(user_prefs::PrefRegistrySyncable* registry);
 
   // WebUIMessageHandler implementation.
   virtual void RegisterMessages() OVERRIDE;