components: Move PrefRegistrySyncable into user_prefs namespace.

chrome/browser/ui/webui/plugins_ui.h

Index: chrome/browser/ui/webui/plugins_ui.h
diff --git a/chrome/browser/ui/webui/plugins_ui.h b/chrome/browser/ui/webui/plugins_ui.h
index bd97b958b38ac01af8d4da8e28f917ad233fca21..a335b8005e9ff623eb4010d4c5a0a9179bfaf053 100644
--- a/chrome/browser/ui/webui/plugins_ui.h
+++ b/chrome/browser/ui/webui/plugins_ui.h
@@ -8,19 +8,21 @@
 #include "content/public/browser/web_ui_controller.h"
 #include "ui/base/layout.h"
 
-class PrefRegistrySyncable;
-
 namespace base {
 class RefCountedMemory;
 }
 
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
 class PluginsUI : public content::WebUIController {
  public:
   explicit PluginsUI(content::WebUI* web_ui);
 
   static base::RefCountedMemory* GetFaviconResourceBytes(
       ui::ScaleFactor scale_factor);
-  static void RegisterUserPrefs(PrefRegistrySyncable* registry);
+  static void RegisterUserPrefs(user_prefs::PrefRegistrySyncable* registry);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PluginsUI);