Adds a WebRTC browser_test with opus dtx enabled.

chrome/test/data/webrtc/peerconnection.js

 /**
  * Copyright 2014 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.
  */
 
 /**
  * The one and only peer connection in this page.
  * @private
  */
@@ skipping 59 matching lines @@
 /**
  * Asks this page to create a local offer.
  *
  * Returns a string on the format ok-(JSON encoded session description).
  *
  * @param {!Object} constraints Any createOffer constraints.
  * @param {string} videoCodec If not null, promotes the specified codec to be
  *     the default video codec, e.g. the first one in the list on the 'm=video'
  *     SDP offer line. |videoCodec| is the case-sensitive codec name, e.g.
  *     'VP8' or 'H264'.
+ * @param {boolean} enableOpusDtx If true, enable Opus Dtx, e.g. append
+ *     'usedtx=1' to the appropriate 'a=fmtp' line.
  */
-function createLocalOffer(constraints, videoCodec = null) {
+function createLocalOffer(constraints,
+                          videoCodec = null,
+                          enableOpusDtx = false) {
   peerConnection_().createOffer(
       function(localOffer) {
         success('createOffer');
 
         setLocalDescription(peerConnection, localOffer);
         if (videoCodec !== null)
           localOffer.sdp = setSdpDefaultVideoCodec(localOffer.sdp, videoCodec);
+        if (enableOpusDtx)
+          localOffer.sdp = setOpusDtxEnabled(localOffer.sdp);
 
         returnToTest('ok-' + JSON.stringify(localOffer));
       },
       function(error) { failure('createOffer', error); },
       constraints);
 }
 
 /**
  * Asks this page to accept an offer and generate an answer.
  *
  * Returns a string on the format ok-(JSON encoded session description).
  *
  * @param {!string} sessionDescJson A JSON-encoded session description of type
  *     'offer'.
  * @param {!Object} constraints Any createAnswer constraints.
+ * @param {boolean} enableOpusDtx If true, enable Opus Dtx, e.g. append
+ *     'usedtx=1' to the appropriate 'a=fmtp' line.
  */
-function receiveOfferFromPeer(sessionDescJson, constraints) {
+function receiveOfferFromPeer(sessionDescJson,
+                              constraints,
+                              enableOpusDtx = false) {
   offer = parseJson_(sessionDescJson);
   if (!offer.type)
     failTest('Got invalid session description from peer: ' + sessionDescJson);
   if (offer.type != 'offer')
     failTest('Expected to receive offer from peer, got ' + offer.type);
 
   var sessionDescription = new RTCSessionDescription(offer);
   peerConnection_().setRemoteDescription(
       sessionDescription,
       function() { success('setRemoteDescription'); },
       function(error) { failure('setRemoteDescription', error); });
 
   peerConnection_().createAnswer(
       function(answer) {
         success('createAnswer');
         setLocalDescription(peerConnection, answer);
+        if (enableOpusDtx)
+          answer.sdp = setOpusDtxEnabled(answer.sdp);
         returnToTest('ok-' + JSON.stringify(answer));
       },
       function(error) { failure('createAnswer', error); },
       constraints);
 }
 
 /**
  * Verifies that the specified codec is the default video codec, e.g. the first
  * one in the list on the 'm=video' SDP answer line. If this is not the case,
  * |failure| occurs.
@@ skipping 15 matching lines @@
   }
   if (expectedVideoCodec !== defaultVideoCodec) {
     failure('verifyDefaultVideoCodec',
              'Expected default video codec ' + expectedVideoCodec +
              ', got ' + defaultVideoCodec + '.');
   }
   returnToTest('ok-verified');
 }
 
 /**
+ * Verifies that Opus Dtx is enabled, e.g. 'usedtx=1' can be found in the
+ * appropriate 'a=fmtp' line. If this is not the case, |failure| occurs.
+ *
+ * @param {!string} sessionDescJson A JSON-encoded session description.
+ */
+function verifyOpusDtxEnabled(sessionDescJson) {
+  var sessionDesc = parseJson_(sessionDescJson);
+  if (!sessionDesc.type) {
+    failure('verifyOpusDtxEnabled',
+             'Invalid session description: ' + sessionDescJson);
+  }
+  checkOpusDtxEnabled(sessionDesc.sdp);
+  returnToTest('ok-verified');
+}
+
+/**
  * Asks this page to accept an answer generated by the peer in response to a
  * previous offer by this page
  *
  * Returns a string ok-accepted-answer on success.
  *
  * @param {!string} sessionDescJson A JSON-encoded session description of type
  *     'answer'.
  */
 function receiveAnswerFromPeer(sessionDescJson) {
   answer = parseJson_(sessionDescJson);
@@ skipping 182 matching lines @@
 function parseJson_(json) {
   // Escape since the \r\n in the SDP tend to get unescaped.
   jsonWithEscapedLineBreaks = json.replace(/\r\n/g, '\\r\\n');
   try {
     return JSON.parse(jsonWithEscapedLineBreaks);
   } catch (exception) {
     failTest('Failed to parse JSON: ' + jsonWithEscapedLineBreaks + ', got ' +
              exception);
   }
 }