Allow dynamic change to WebRTC's multiple_routes_enabled preference.

chrome/browser/ui/prefs/prefs_tab_helper.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/prefs/prefs_tab_helper.h"
 
 #include <set>
 #include <string>
 
 #include "base/memory/singleton.h"
@@ skipping 334 matching lines @@
  public:
   explicit PrefWatcher(Profile* profile) : profile_(profile) {
     pref_change_registrar_.Init(profile_->GetPrefs());
 
     base::Closure renderer_callback = base::Bind(
         &PrefWatcher::UpdateRendererPreferences, base::Unretained(this));
     pref_change_registrar_.Add(prefs::kAcceptLanguages, renderer_callback);
     pref_change_registrar_.Add(prefs::kEnableDoNotTrack, renderer_callback);
     pref_change_registrar_.Add(prefs::kEnableReferrers, renderer_callback);
 
+#if defined(ENABLE_WEBRTC)
+    pref_change_registrar_.Add(prefs::kWebRTCMultipleRoutesEnabled,
+                               renderer_callback);
+#endif
+
 #if !defined(OS_MACOSX)
     pref_change_registrar_.Add(prefs::kFullscreenAllowed, renderer_callback);
 #endif
 
     PrefChangeRegistrar::NamedChangeCallback webkit_callback = base::Bind(
         &PrefWatcher::OnWebPrefChanged, base::Unretained(this));
     for (int i = 0; i < kPrefsToObserveLength; ++i) {
       const char* pref_name = kPrefsToObserve[i];
       pref_change_registrar_.Add(pref_name, webkit_callback);
     }
@@ skipping 371 matching lines @@
   }
 }
 
 void PrefsTabHelper::OnWebPrefChanged(const std::string& pref_name) {
 #if !defined(OS_ANDROID)
   OnFontFamilyPrefChanged(pref_name);
 #endif
 
   web_contents_->GetRenderViewHost()->OnWebkitPreferencesChanged();
 }