components: Move PrefRegistrySyncable into user_prefs namespace.

chrome/browser/extensions/component_loader.h

Index: chrome/browser/extensions/component_loader.h
diff --git a/chrome/browser/extensions/component_loader.h b/chrome/browser/extensions/component_loader.h
index baa28a1c3f1ef9256cfbfd2091d65867f58c5c84..886f21f852daf3e4e6317987e1ecad486f5592e1 100644
--- a/chrome/browser/extensions/component_loader.h
+++ b/chrome/browser/extensions/component_loader.h
@@ -15,7 +15,10 @@
 
 class ExtensionServiceInterface;
 class PrefService;
+
+namespace user_prefs {
 class PrefRegistrySyncable;
+}
 
 namespace extensions {
 
@@ -80,7 +83,7 @@ class ComponentLoader {
   // platforms this |skip_session_components| is expected to be unset.
   void AddDefaultComponentExtensions(bool skip_session_components);
 
-  static void RegisterUserPrefs(PrefRegistrySyncable* registry);
+  static void RegisterUserPrefs(user_prefs::PrefRegistrySyncable* registry);
 
   // Parse the given JSON manifest. Returns NULL if it cannot be parsed, or if
   // if the result is not a DictionaryValue.