Add policy to control valid UDP port range in WebRTC

chrome/browser/ui/browser_ui_prefs.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/browser_ui_prefs.h"
 
 #include "build/build_config.h"
 #include "chrome/browser/first_run/first_run.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/pref_names.h"
@@ skipping 106 matching lines @@
   registry->RegisterBooleanPref(
       prefs::kEnableDoNotTrack,
       false,
       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
 #if defined(ENABLE_WEBRTC)
   // TODO(guoweis): Remove next 2 options at M50.
   registry->RegisterBooleanPref(prefs::kWebRTCMultipleRoutesEnabled, true);
   registry->RegisterBooleanPref(prefs::kWebRTCNonProxiedUdpEnabled, true);
   registry->RegisterStringPref(prefs::kWebRTCIPHandlingPolicy,
                                content::kWebRTCIPHandlingDefault);
+  registry->RegisterStringPref(prefs::kWebRTCUDPPortRange, std::string());
 #endif
 
   // Dictionaries to keep track of default tasks in the file browser.
   registry->RegisterDictionaryPref(
       prefs::kDefaultTasksByMimeType,
       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
   registry->RegisterDictionaryPref(
       prefs::kDefaultTasksBySuffix,
       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
 
@@ skipping 20 matching lines @@
   registry->RegisterBooleanPref(
       prefs::kHideFullscreenToolbar,
       false,
       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
 #else
   registry->RegisterBooleanPref(prefs::kFullscreenAllowed, true);
 #endif
 }
 
 }  // namespace chrome