components: Move PrefRegistrySyncable into user_prefs namespace.

chrome/browser/chromeos/preferences.h

Index: chrome/browser/chromeos/preferences.h
diff --git a/chrome/browser/chromeos/preferences.h b/chrome/browser/chromeos/preferences.h
index 6f31f36f3dbd3675beafec0e0f6472269f11a616..c1bab86bad7eece9db0f9d8d35ccfbea683106a0 100644
--- a/chrome/browser/chromeos/preferences.h
+++ b/chrome/browser/chromeos/preferences.h
@@ -14,14 +14,18 @@
 #include "chrome/browser/prefs/pref_service_syncable_observer.h"
 
 class PrefRegistrySimple;
-class PrefRegistrySyncable;
 class PrefService;
 class PrefServiceSyncable;
 
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
 namespace chromeos {
+
 namespace input_method {
 class InputMethodManager;
-}  // namespace input_method
+}
 
 // The Preferences class handles Chrome OS preferences. When the class
 // is first initialized, it will initialize the OS settings to what's stored in
@@ -36,7 +40,7 @@ class Preferences : public PrefServiceSyncableObserver {
 
   // These method will register the prefs associated with Chrome OS settings.
   static void RegisterPrefs(PrefRegistrySimple* registry);
-  static void RegisterUserPrefs(PrefRegistrySyncable* registry);
+  static void RegisterUserPrefs(user_prefs::PrefRegistrySyncable* registry);
 
   // This method will initialize Chrome OS settings to values in user prefs.
   void Init(PrefServiceSyncable* prefs);