Adds a WebRTC browser_test with opus dtx enabled.

chrome/browser/extensions/api/webrtc_logging_private/webrtc_event_log_apitest.cc

 // Copyright 2016 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 <memory>
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/files/file_path_watcher.h"
 #include "base/json/json_writer.h"
@@ skipping 143 matching lines @@
   ASSERT_TRUE(embedded_test_server()->Start());
 
   content::WebContents* left_tab =
       OpenTestPageAndGetUserMediaInNewTab(kMainWebrtcTestHtmlPage);
   content::WebContents* right_tab =
       OpenTestPageAndGetUserMediaInNewTab(kMainWebrtcTestHtmlPage);
 
   SetupPeerconnectionWithLocalStream(left_tab);
   SetupPeerconnectionWithLocalStream(right_tab);
 
-  NegotiateCall(left_tab, right_tab, "VP8");
+  SetDefaultVideoCodec(left_tab, "VP8");
+  SetDefaultVideoCodec(right_tab, "VP8");
+  NegotiateCall(left_tab, right_tab);
 
   StartDetectingVideo(left_tab, "remote-view");
   StartDetectingVideo(right_tab, "remote-view");
 
   // Start the event log.
   const int seconds = 0;
   base::ListValue start_params;
   AppendTabIdAndUrl(&start_params, left_tab);
   start_params.AppendInteger(seconds);
   scoped_refptr<WebrtcLoggingPrivateStartWebRtcEventLoggingFunction>
@@ skipping 69 matching lines @@
   ASSERT_TRUE(embedded_test_server()->Start());
 
   content::WebContents* left_tab =
       OpenTestPageAndGetUserMediaInNewTab(kMainWebrtcTestHtmlPage);
   content::WebContents* right_tab =
       OpenTestPageAndGetUserMediaInNewTab(kMainWebrtcTestHtmlPage);
 
   SetupPeerconnectionWithLocalStream(left_tab);
   SetupPeerconnectionWithLocalStream(right_tab);
 
-  NegotiateCall(left_tab, right_tab, "VP8");
+  SetDefaultVideoCodec(left_tab, "VP8");
+  SetDefaultVideoCodec(right_tab, "VP8");
+  NegotiateCall(left_tab, right_tab);
 
   StartDetectingVideo(left_tab, "remote-view");
   StartDetectingVideo(right_tab, "remote-view");
 
   // Start the event log. RunFunctionAndReturnSingleResult will block until a
   // result is available, which happens when the logging stops after 1 second.
   const int seconds = 1;
   base::ListValue start_params;
   AppendTabIdAndUrl(&start_params, left_tab);
   start_params.AppendInteger(seconds);
@@ skipping 38 matching lines @@
   ASSERT_TRUE(waiter->Start()) << "ERROR watching for "
                                << full_file_name.value();
   ASSERT_TRUE(waiter->WaitForFile());
   ASSERT_TRUE(base::PathExists(full_file_name));
   EXPECT_TRUE(base::GetFileSize(full_file_name, &file_size));
   EXPECT_GT(file_size, 0);
 
   // Clean up.
   base::DeleteFile(full_file_name, false);
 }