Reuse one UserPolicySigninService for Android and iOS.

chrome/browser/policy/cloud/user_policy_signin_service_factory.cc

Index: chrome/browser/policy/cloud/user_policy_signin_service_factory.cc
diff --git a/chrome/browser/policy/cloud/user_policy_signin_service_factory.cc b/chrome/browser/policy/cloud/user_policy_signin_service_factory.cc
index 337ada1cb5bebe5c566ca54a4a330e6be3099794..f4af06f472ca5eb098ca5144cbbfbc6d15f75326 100644
--- a/chrome/browser/policy/cloud/user_policy_signin_service_factory.cc
+++ b/chrome/browser/policy/cloud/user_policy_signin_service_factory.cc
@@ -17,10 +17,8 @@
 #include "components/user_prefs/pref_registry_syncable.h"
 #include "net/url_request/url_request_context_getter.h"
 
-#if defined(OS_ANDROID)
-#include "chrome/browser/policy/cloud/user_policy_signin_service_android.h"
-#elif defined(OS_IOS)
-#include "chrome/browser/policy/cloud/user_policy_signin_service_ios.h"
+#if defined(OS_ANDROID) || defined(OS_IOS)
+#include "chrome/browser/policy/cloud/user_policy_signin_service_mobile.h"
 #else
 #include "chrome/browser/policy/cloud/user_policy_signin_service.h"
 #endif
@@ -99,7 +97,7 @@ UserPolicySigninServiceFactory::ServiceIsCreatedWithBrowserContext() const {
 
 void UserPolicySigninServiceFactory::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* user_prefs) {
-#if defined(OS_ANDROID)
+#if defined(OS_ANDROID) || defined(OS_IOS)
   user_prefs->RegisterInt64Pref(
       prefs::kLastPolicyCheckTime,
       0,