Add `privacy.network.webRTCMultipleRoutesEnabled` to extensions API.

chrome/browser/extensions/api/preference/preference_apitest.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 "base/prefs/pref_service.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/net/prediction_options.h"
@@ skipping 100 matching lines @@
   prefs->SetBoolean(prefs::kBlockThirdPartyCookies, true);
   prefs->SetBoolean(prefs::kEnableHyperlinkAuditing, false);
   prefs->SetBoolean(prefs::kEnableReferrers, false);
   prefs->SetBoolean(prefs::kEnableTranslate, false);
   prefs->SetInteger(prefs::kNetworkPredictionOptions,
                     chrome_browser_net::NETWORK_PREDICTION_NEVER);
   prefs->SetBoolean(password_manager::prefs::kPasswordManagerSavingEnabled,
                     false);
   prefs->SetBoolean(prefs::kSafeBrowsingEnabled, false);
   prefs->SetBoolean(prefs::kSearchSuggestEnabled, false);
+#if defined(ENABLE_WEBRTC)
+  prefs->SetBoolean(prefs::kWebRTCMultipleRoutesEnabled, false);
+#endif
 
   const char kExtensionPath[] = "preference/standard";
 
   EXPECT_TRUE(RunExtensionSubtest(kExtensionPath, "test.html")) << message_;
   CheckPreferencesSet();
 
   // The settings should not be reset when the extension is reloaded.
   ReloadExtension(last_loaded_extension_id());
   CheckPreferencesSet();
 
@@ skipping 197 matching lines @@
   listener_incognito10.Reply("ok");
 
   EXPECT_TRUE(catcher.GetNextResult()) << catcher.message();
   EXPECT_TRUE(catcher_incognito.GetNextResult()) << catcher.message();
 }
 
 IN_PROC_BROWSER_TEST_F(ExtensionPreferenceApiTest, DataReductionProxy) {
   EXPECT_TRUE(RunExtensionTest("preference/data_reduction_proxy")) <<
       message_;
 }