RTCRtpSender with track behind RuntimeEnabled flag

chrome/browser/media/webrtc/webrtc_rtp_browsertest.cc

 // Copyright 2017 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 "chrome/browser/media/webrtc/webrtc_browsertest_base.h"
 #include "content/public/common/content_switches.h"
 #include "media/base/media_switches.h"
 
 static const char kMainWebrtcTestHtmlPage[] = "/webrtc/webrtc_jsep01_test.html";
 
 class WebRtcRtpBrowserTest : public WebRtcTestBase {
  public:
   WebRtcRtpBrowserTest() : left_tab_(nullptr), right_tab_(nullptr) {}
 
   void SetUpInProcessBrowserTestFixture() override {
     DetectErrorsInJavaScript();
   }
 
   void SetUpCommandLine(base::CommandLine* command_line) override {
     command_line->AppendSwitch(switches::kUseFakeDeviceForMediaStream);
+    command_line->AppendSwitchASCII(switches::kEnableBlinkFeatures,
+                                    "RTCRtpSender");
   }
 
  protected:
   void StartServerAndOpenTabs() {
     ASSERT_TRUE(embedded_test_server()->Start());
     left_tab_ = OpenTestPageAndGetUserMediaInNewTab(kMainWebrtcTestHtmlPage);
     right_tab_ = OpenTestPageAndGetUserMediaInNewTab(kMainWebrtcTestHtmlPage);
   }
 
   content::WebContents* left_tab_;
   content::WebContents* right_tab_;
 };
 
+IN_PROC_BROWSER_TEST_F(WebRtcRtpBrowserTest, GetSenders) {
+  StartServerAndOpenTabs();
+
+  SetupPeerconnectionWithoutLocalStream(left_tab_);
+  CreateAndAddStreams(left_tab_, 3);
+
+  SetupPeerconnectionWithoutLocalStream(right_tab_);
+  CreateAndAddStreams(right_tab_, 1);
+
+  NegotiateCall(left_tab_, right_tab_);
+
+  VerifyRtpSenders(left_tab_, 6);
+  VerifyRtpSenders(right_tab_, 2);
+}
+
 IN_PROC_BROWSER_TEST_F(WebRtcRtpBrowserTest, GetReceivers) {
   StartServerAndOpenTabs();
 
   SetupPeerconnectionWithoutLocalStream(left_tab_);
   CreateAndAddStreams(left_tab_, 3);
 
   SetupPeerconnectionWithoutLocalStream(right_tab_);
   CreateAndAddStreams(right_tab_, 1);
 
   NegotiateCall(left_tab_, right_tab_);
 
   VerifyRtpReceivers(left_tab_, 2);
   VerifyRtpReceivers(right_tab_, 6);
 }