components: Move PrefRegistrySyncable into user_prefs namespace.

chrome/browser/policy/cloud/user_policy_signin_service_factory.h

Index: chrome/browser/policy/cloud/user_policy_signin_service_factory.h
diff --git a/chrome/browser/policy/cloud/user_policy_signin_service_factory.h b/chrome/browser/policy/cloud/user_policy_signin_service_factory.h
index 8f09a59e2a8126161e8bb4fc4a7a42ab54a1bb38..cde10e8bb0f6e9a68b6745cd3ae30d6855fcd0a8 100644
--- a/chrome/browser/policy/cloud/user_policy_signin_service_factory.h
+++ b/chrome/browser/policy/cloud/user_policy_signin_service_factory.h
@@ -8,7 +8,9 @@
 #include "base/memory/singleton.h"
 #include "chrome/browser/profiles/profile_keyed_service_factory.h"
 
+namespace user_prefs {
 class PrefRegistrySyncable;
+}
 
 namespace policy {
 
@@ -34,7 +36,8 @@ class UserPolicySigninServiceFactory : public ProfileKeyedServiceFactory {
   virtual bool ServiceIsCreatedWithProfile() const OVERRIDE;
 
   // Register the preferences related to cloud-based user policy.
-  virtual void RegisterUserPrefs(PrefRegistrySyncable* registry) OVERRIDE;
+  virtual void RegisterUserPrefs(
+      user_prefs::PrefRegistrySyncable* registry) OVERRIDE;
 
  private:
   friend struct DefaultSingletonTraits<UserPolicySigninServiceFactory>;