components: Move PrefRegistrySyncable into user_prefs namespace.

chrome/browser/extensions/api/tabs/tabs_api.h

Index: chrome/browser/extensions/api/tabs/tabs_api.h
diff --git a/chrome/browser/extensions/api/tabs/tabs_api.h b/chrome/browser/extensions/api/tabs/tabs_api.h
index 5df900ac99611045078b0c605db02c937c66f072..bdb062a2a8c9e47f572ed193c22c473a1f7b649a 100644
--- a/chrome/browser/extensions/api/tabs/tabs_api.h
+++ b/chrome/browser/extensions/api/tabs/tabs_api.h
@@ -18,7 +18,6 @@
 
 class BackingStore;
 class GURL;
-class PrefRegistrySyncable;
 class SkBitmap;
 
 namespace base {
@@ -37,6 +36,10 @@ struct InjectDetails;
 }  // namespace api
 }  // namespace extensions
 
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
 // Windows
 class WindowsGetFunction : public SyncExtensionFunction {
   virtual ~WindowsGetFunction() {}
@@ -176,7 +179,7 @@ class TabsDetectLanguageFunction : public AsyncExtensionFunction,
 };
 class TabsCaptureVisibleTabFunction : public AsyncExtensionFunction {
  public:
-  static void RegisterUserPrefs(PrefRegistrySyncable* registry);
+  static void RegisterUserPrefs(user_prefs::PrefRegistrySyncable* registry);
 
  protected:
   enum ImageFormat {