Reland of "Adds a WebRTC browser_test with opus dtx enabled.".

chrome/browser/media/webrtc_browsertest.cc

 // Copyright 2013 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/command_line.h"
 #include "base/strings/stringprintf.h"
 #include "build/build_config.h"
 #include "chrome/browser/media/webrtc_browsertest_base.h"
 #include "chrome/browser/media/webrtc_browsertest_common.h"
 #include "chrome/browser/ui/browser.h"
@@ skipping 44 matching lines @@
       const std::string& video_codec = WebRtcTestBase::kUseDefaultVideoCodec,
       const std::string& offer_cert_keygen_alg =
           WebRtcTestBase::kUseDefaultCertKeygen,
       const std::string& answer_cert_keygen_alg =
           WebRtcTestBase::kUseDefaultCertKeygen) {
     StartServerAndOpenTabs();
 
     SetupPeerconnectionWithLocalStream(left_tab_, offer_cert_keygen_alg);
     SetupPeerconnectionWithLocalStream(right_tab_, answer_cert_keygen_alg);
 
-    NegotiateCall(left_tab_, right_tab_, video_codec);
+    if (!video_codec.empty()) {
+      SetDefaultVideoCodec(left_tab_, video_codec);
+      SetDefaultVideoCodec(right_tab_, video_codec);
+    }
+    NegotiateCall(left_tab_, right_tab_);
 
     DetectVideoAndHangUp();
   }
 
   void RunsAudioVideoWebRTCCallInTwoTabsWithClonedCertificate(
       const std::string& cert_keygen_alg =
           WebRtcTestBase::kUseDefaultCertKeygen) {
     StartServerAndOpenTabs();
 
     // Generate and clone a certificate, resulting in JavaScript variable
     // |gCertificateClone| being set to the resulting clone.
     DeleteDatabase(left_tab_);
     OpenDatabase(left_tab_);
     GenerateAndCloneCertificate(left_tab_, cert_keygen_alg);
     CloseDatabase(left_tab_);
     DeleteDatabase(left_tab_);
 
     SetupPeerconnectionWithCertificateAndLocalStream(
         left_tab_, "gCertificateClone");
     SetupPeerconnectionWithLocalStream(right_tab_, cert_keygen_alg);
 
-    NegotiateCall(left_tab_, right_tab_, WebRtcTestBase::kUseDefaultVideoCodec);
+    NegotiateCall(left_tab_, right_tab_);
 
     DetectVideoAndHangUp();
   }
 
 protected:
   void StartServerAndOpenTabs() {
     ASSERT_TRUE(embedded_test_server()->Start());
     left_tab_ = OpenTestPageAndGetUserMediaInNewTab(kMainWebrtcTestHtmlPage);
     right_tab_ = OpenTestPageAndGetUserMediaInNewTab(kMainWebrtcTestHtmlPage);
   }
@@ skipping 99 matching lines @@
                        RunsAudioVideoWebRTCCallInTwoTabsGetStats) {
   StartServerAndOpenTabs();
   SetupPeerconnectionWithLocalStream(left_tab_);
   SetupPeerconnectionWithLocalStream(right_tab_);
   NegotiateCall(left_tab_, right_tab_);
 
   VerifyStatsGenerated(left_tab_);
 
   DetectVideoAndHangUp();
 }