--- a/dom/media/tests/mochitest/mochitest.ini
+++ b/dom/media/tests/mochitest/mochitest.ini
@@ -127,16 +127,20 @@ skip-if = android_version == '18'
 [test_peerConnection_basicAudioDynamicPtMissingRtpmap.html]
 skip-if = (android_version == '18') # android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_basicAudioVerifyRtpHeaderExtensions.html]
 skip-if = (android_version == '18') # android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_basicAudioVideo.html]
 skip-if = (android_version == '18') # android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_basicAudioVideoCombined.html]
 skip-if = toolkit == 'android'  # Bug 1189784
+[test_peerConnection_basicAudioVideoVerifyExtmap.html]
+skip-if = (android_version == '18') # android(Bug 1189784, timeouts on 4.3 emulator)
+[test_peerConnection_basicAudioVideoVerifyExtmapSendonly.html]
+skip-if = (android_version == '18') # android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_basicAudioVideoNoBundle.html]
 skip-if = (android_version == '18') # android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_basicAudioVideoNoBundleNoRtcpMux.html]
 skip-if = android_version == '18' # android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_basicAudioVideoNoRtcpMux.html]
 skip-if = android_version == '18' # android(Bug 1189784, timeouts on 4.3 emulator)
 [test_peerConnection_basicAudioVideoTransceivers.html]
 skip-if = android_version == '18' # android(Bug 1189784, timeouts on 4.3 emulator)

--- a/dom/media/tests/mochitest/sdpUtils.js
+++ b/dom/media/tests/mochitest/sdpUtils.js
@@ -21,29 +21,72 @@ findCodecId: function(sdp, format, offse
   // match[1] is the first parenthesis group
   return match[1];
 },
 
 // Finds all the extmap ids in the given sdp.  Note that this does NOT
 // consider m-sections, so a more generic version would need to
 // look at each m-section separately.
 findExtmapIds: function(sdp) {
-        var sdpExtmapIds = [];
-        extmapRegEx = /^a=extmap:([0-9+])/gm;
-        // must call exec on the regex to get each match in the string
-        while ((searchResults = extmapRegEx.exec(sdp))
-               !== null) {
-          // returned array has the matched text as the first item,
-          // and then one item for each capturing parenthesis that
-          // matched containing the text that was captured.
-          sdpExtmapIds.push(searchResults[1]);
-        }
+  var sdpExtmapIds = [];
+  extmapRegEx = /^a=extmap:([0-9+])/gm;
+  // must call exec on the regex to get each match in the string
+  while ((searchResults = extmapRegEx.exec(sdp))
+         !== null) {
+    // returned array has the matched text as the first item,
+    // and then one item for each capturing parenthesis that
+    // matched containing the text that was captured.
+    sdpExtmapIds.push(searchResults[1]);
+  }
   return sdpExtmapIds;
 },
 
+findExtmapIdsUrnsDirections: function(sdp) {
+  var sdpExtmap = [];
+  extmapRegEx = /^a=extmap:([0-9+])([A-Za-z/]*) ([A-Za-z0-9_:\-\/\.]+)/gm;
+  // must call exec on the regex to get each match in the string
+  while ((searchResults = extmapRegEx.exec(sdp))
+         !== null) {
+    // returned array has the matched text as the first item,
+    // and then one item for each capturing parenthesis that
+    // matched containing the text that was captured.
+    var idUrn = [];
+    idUrn.push(searchResults[1]);
+    idUrn.push(searchResults[3]);
+    idUrn.push(searchResults[2].slice(1));
+    sdpExtmap.push(idUrn);
+  }
+  return sdpExtmap;
+},
+
+verify_unique_extmap_ids: function(sdp) {
+  const sdpExtmapIds = sdputils.findExtmapIdsUrnsDirections(sdp);
+
+  return sdpExtmapIds.reduce(function(result, item, index) {
+    const [id, urn, dir] = item;
+    ok((!(id in result)) ||
+      ((result[id][0] === urn) && (result[id][1] === dir)),
+        "ID " + id + " is unique ID for " + urn + " and direction " + dir);
+    result[id] = [urn, dir];
+    return result;
+  }, {});
+},
+
+getMSections: function(sdp) {
+  return sdp.split(new RegExp('^m=', 'gm')).slice(1);
+},
+
+getAudioMSections: function(sdp) {
+  return this.getMSections(sdp).filter(section => section.startsWith('audio'))
+},
+
+getVideoMSections: function(sdp) {
+  return this.getMSections(sdp).filter(section => section.startsWith('video'))
+},
+
 checkSdpAfterEndOfTrickle: function(sdp, testOptions, label) {
   info("EOC-SDP: " + JSON.stringify(sdp));
 
   ok(sdp.sdp.includes("a=end-of-candidates"), label + ": SDP contains end-of-candidates");
   sdputils.checkSdpCLineNotDefault(sdp.sdp, label);
 
   if (testOptions.rtcpmux) {
     ok(sdp.sdp.includes("a=rtcp-mux"), label + ": SDP contains rtcp-mux");

copy from dom/media/tests/mochitest/test_peerConnection_basicAudioVideo.html
copy to dom/media/tests/mochitest/test_peerConnection_basicAudioVideoVerifyExtmap.html
--- a/dom/media/tests/mochitest/test_peerConnection_basicAudioVideo.html
+++ b/dom/media/tests/mochitest/test_peerConnection_basicAudioVideoVerifyExtmap.html
@@ -2,23 +2,91 @@
 <html>
 <head>
   <script type="application/javascript" src="pc.js"></script>
 </head>
 <body>
 <pre id="test">
 <script type="application/javascript">
   createHTML({
-    bug: "796890",
-    title: "Basic audio/video (separate) peer connection"
+    bug: "1406529",
+    title: "Verify SDP extmap attribute for sendrecv connection"
   });
 
   var test;
   runNetworkTest(function (options) {
     test = new PeerConnectionTest(options);
     test.setMediaConstraints([{audio: true}, {video: true}],
                              [{audio: true}, {video: true}]);
+
+    test.chain.insertAfter('PC_LOCAL_SET_LOCAL_DESCRIPTION', [
+      async function PC_LOCAL_CHECK_SDP_OFFER_EXTMAP() {
+        sdputils.verify_unique_extmap_ids(test.originalOffer.sdp);
+
+        const audio = sdputils.findExtmapIdsUrnsDirections(
+            sdputils.getAudioMSections(test.originalOffer.sdp));
+        const expected_audio = [
+          /* Please modify this list when you add or remove RTP header
+          extensions. */
+          ["1", "urn:ietf:params:rtp-hdrext:ssrc-audio-level", ""],
+          ["2", "urn:ietf:params:rtp-hdrext:csrc-audio-level", "recvonly"],
+          ["3", "urn:ietf:params:rtp-hdrext:sdes:mid", ""],
+        ];
+        // *Ugh* ...
+        ok(JSON.stringify(audio) ===
+           JSON.stringify(expected_audio),
+           "List of offer audio URNs meets expected values");
+
+        const video = sdputils.findExtmapIdsUrnsDirections(
+            sdputils.getVideoMSections(test.originalOffer.sdp));
+        const expected_video = [
+          /* Please modify this list when you add or remove RTP header
+          extensions. */
+          ["3", "urn:ietf:params:rtp-hdrext:sdes:mid", ""],
+          ["4", "http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time", ""],
+          ["5", "urn:ietf:params:rtp-hdrext:toffset", ""],
+        ];
+        // *Ugh* ...
+        ok(JSON.stringify(video) ===
+           JSON.stringify(expected_video),
+           "List of offer video URNs meets expected values");
+      }
+    ]);
+
+    test.chain.removeAfter('PC_REMOTE_SET_LOCAL_DESCRIPTION');
+    test.chain.append([
+      async function PC_REMOTE_CHECK_SDP_ANSWER_EXTMAP() {
+        sdputils.verify_unique_extmap_ids(test.originalAnswer.sdp);
+
+        const audio = sdputils.findExtmapIdsUrnsDirections(
+            sdputils.getAudioMSections(test.originalAnswer.sdp));
+        const expected_audio = [
+          /* Please modify this list when you add or remove RTP header
+          extensions. */
+          ["1", "urn:ietf:params:rtp-hdrext:ssrc-audio-level",""],
+          ["3", "urn:ietf:params:rtp-hdrext:sdes:mid",""],
+        ];
+        // *Ugh* ...
+        ok(JSON.stringify(audio) ===
+           JSON.stringify(expected_audio),
+           "List of answer audio URNs meets expected values");
+
+        const video = sdputils.findExtmapIdsUrnsDirections(
+            sdputils.getVideoMSections(test.originalAnswer.sdp));
+        const expected_video = [
+          /* Please modify this list when you add or remove RTP header
+          extensions. */
+          ["3", "urn:ietf:params:rtp-hdrext:sdes:mid",""],
+          ["4", "http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time",""],
+          ["5", "urn:ietf:params:rtp-hdrext:toffset",""],
+        ];
+        ok(JSON.stringify(video) ===
+           JSON.stringify(expected_video),
+           "List of answer video URNs meets expected values");
+      }
+    ]);
+
     test.run();
   });
 </script>
 </pre>
 </body>
 </html>

copy from dom/media/tests/mochitest/test_peerConnection_basicAudioVideo.html
copy to dom/media/tests/mochitest/test_peerConnection_basicAudioVideoVerifyExtmapSendonly.html
--- a/dom/media/tests/mochitest/test_peerConnection_basicAudioVideo.html
+++ b/dom/media/tests/mochitest/test_peerConnection_basicAudioVideoVerifyExtmapSendonly.html
@@ -2,23 +2,91 @@
 <html>
 <head>
   <script type="application/javascript" src="pc.js"></script>
 </head>
 <body>
 <pre id="test">
 <script type="application/javascript">
   createHTML({
-    bug: "796890",
-    title: "Basic audio/video (separate) peer connection"
+    bug: "1406529",
+    title: "Verify SDP extmap attribute for sendonly connection"
   });
 
   var test;
   runNetworkTest(function (options) {
     test = new PeerConnectionTest(options);
     test.setMediaConstraints([{audio: true}, {video: true}],
-                             [{audio: true}, {video: true}]);
+                             []);
+
+    test.chain.insertAfter('PC_LOCAL_SET_LOCAL_DESCRIPTION', [
+      async function PC_LOCAL_CHECK_SDP_OFFER_EXTMAP() {
+        sdputils.verify_unique_extmap_ids(test.originalOffer.sdp);
+
+        const audio = sdputils.findExtmapIdsUrnsDirections(
+            sdputils.getAudioMSections(test.originalOffer.sdp));
+        const expected_audio = [
+          /* Please modify this list when you add or remove RTP header
+          extensions. */
+          ["1", "urn:ietf:params:rtp-hdrext:ssrc-audio-level", ""],
+          ["2", "urn:ietf:params:rtp-hdrext:csrc-audio-level", "recvonly"],
+          ["3", "urn:ietf:params:rtp-hdrext:sdes:mid", ""],
+        ];
+        // *Ugh* ...
+        ok(JSON.stringify(audio) ===
+           JSON.stringify(expected_audio),
+           "List of offer audio URNs meets expected values");
+
+        const video = sdputils.findExtmapIdsUrnsDirections(
+            sdputils.getVideoMSections(test.originalOffer.sdp));
+        const expected_video = [
+          /* Please modify this list when you add or remove RTP header
+          extensions. */
+          ["3", "urn:ietf:params:rtp-hdrext:sdes:mid", ""],
+          ["4", "http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time", ""],
+          ["5", "urn:ietf:params:rtp-hdrext:toffset", ""],
+        ];
+        // *Ugh* ...
+        ok(JSON.stringify(video) ===
+           JSON.stringify(expected_video),
+           "List of offer video URNs meets expected values");
+      }
+    ]);
+
+    test.chain.removeAfter('PC_REMOTE_SET_LOCAL_DESCRIPTION');
+    test.chain.append([
+      async function PC_REMOTE_CHECK_SDP_ANSWER_EXTMAP() {
+        sdputils.verify_unique_extmap_ids(test.originalAnswer.sdp);
+
+        const audio = sdputils.findExtmapIdsUrnsDirections(
+            sdputils.getAudioMSections(test.originalAnswer.sdp));
+        const expected_audio = [
+          /* Please modify this list when you add or remove RTP header
+          extensions. */
+          ["1", "urn:ietf:params:rtp-hdrext:ssrc-audio-level",""],
+          ["3", "urn:ietf:params:rtp-hdrext:sdes:mid",""],
+        ];
+        // *Ugh* ...
+        ok(JSON.stringify(audio) ===
+           JSON.stringify(expected_audio),
+           "List of answer audio URNs meets expected values");
+
+        const video = sdputils.findExtmapIdsUrnsDirections(
+            sdputils.getVideoMSections(test.originalAnswer.sdp));
+        const expected_video = [
+          /* Please modify this list when you add or remove RTP header
+          extensions. */
+          ["3", "urn:ietf:params:rtp-hdrext:sdes:mid",""],
+          ["4", "http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time",""],
+          ["5", "urn:ietf:params:rtp-hdrext:toffset",""],
+        ];
+        ok(JSON.stringify(video) ===
+           JSON.stringify(expected_video),
+           "List of answer video URNs meets expected values");
+      }
+    ]);
+
     test.run();
   });
 </script>
 </pre>
 </body>
 </html>