Add a SigninAllowed policy.

chrome/browser/ui/webui/sync_promo/sync_promo_ui.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/sync_promo/sync_promo_ui.h"
 
 #include "base/command_line.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
 #include "base/stringprintf.h"
@@ skipping 109 matching lines @@
 #if defined(OS_CHROMEOS)
   // There's no need to show the sync promo on cros since cros users are logged
   // into sync already.
   return false;
 #else
 
   // Don't bother if we don't have any kind of network connection.
   if (net::NetworkChangeNotifier::IsOffline())
     return false;
 
+  // Honor the signin policy.
+  if (!profile->GetOriginalProfile()->IsSigninAllowed())
+    return false;
   // Display the signin promo if the user is not signed in.
   SigninManager* signin = SigninManagerFactory::GetForProfile(
       profile->GetOriginalProfile());
   return signin->GetAuthenticatedUsername().empty();
 #endif
 }
 
 // static
 void SyncPromoUI::RegisterUserPrefs(PrefServiceSyncable* prefs) {
   prefs->RegisterIntegerPref(prefs::kSyncPromoStartupCount, 0,
@@ skipping 159 matching lines @@
       g_force_web_based_signin_flow;
 #else
   return false;
 #endif
 }
 
 // static
 void SyncPromoUI::ForceWebBasedSigninFlowForTesting(bool force) {
   g_force_web_based_signin_flow = force;
 }