components: Move PrefRegistrySyncable into user_prefs namespace.

chrome/browser/profiles/chrome_version_service.h

Index: chrome/browser/profiles/chrome_version_service.h
diff --git a/chrome/browser/profiles/chrome_version_service.h b/chrome/browser/profiles/chrome_version_service.h
index ceeb99942354173c560a294233db3907967b2c53..75aecef46dbe7e45880289a76747cf4c5551b4ab 100644
--- a/chrome/browser/profiles/chrome_version_service.h
+++ b/chrome/browser/profiles/chrome_version_service.h
@@ -10,14 +10,17 @@
 #include "base/basictypes.h"
 
 class PrefService;
+
+namespace user_prefs {
 class PrefRegistrySyncable;
+}
 
 // This service manages a pref which is used to determine the version of
 // Chrome by which the profile was created.
 class ChromeVersionService {
  public:
   // Register the user pref we use.
-  static void RegisterUserPrefs(PrefRegistrySyncable* registry);
+  static void RegisterUserPrefs(user_prefs::PrefRegistrySyncable* registry);
 
   // Sets the version string in the pref for the current profile.
   static void SetVersion(PrefService* prefs, const std::string& version);