Give performance_browser_tests lots of love and attention.

chrome/test/data/extensions/api_test/cast_streaming/performance.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.
 
 // Run a cast v2 mirroring session for 10 seconds.
 
 chrome.test.runTests([
   function sendTestPatterns() {
     // The receive port changes between browser_test invocations, and is passed
     // as an query parameter in the URL.
-    var recvPort;
+    let recvPort;
+    let autoThrottling;
+    let aesKey;
+    let aesIvMask;
     try {
-      recvPort = parseInt(window.location.search.substring("?port=".length));
+      const params = window.location.search;
+      recvPort = parseInt(params.match(/(\?|&)port=(\d+)/)[2]);
       chrome.test.assertTrue(recvPort > 0);
+      autoThrottling = (params.match(/(\?|&)autoThrottling=(true|false)/)[2] ==
+                            'true');
+      aesKey = params.match(/(\?|&)aesKey=([0-9A-F]{32})/)[2];
+      aesIvMask = params.match(/(\?|&)aesIvMask=([0-9A-F]{32})/)[2];
     } catch (err) {
-      chrome.test.fail("Error parsing ?port=### -- " + err.message);
+      chrome.test.fail("Error parsing params -- " + err.message);
       return;
     }
 
-    var width = 1920;
-    var height = 1080;
-    var frameRate = 30;
-
+    const kMaxFrameRate = 30;
     chrome.tabCapture.capture(
         { video: true,
           audio: true,
           videoConstraints: {
-            mandatory: {
-              minWidth: width,
-              minHeight: height,
-              maxWidth: width,
-              maxHeight: height,
-              maxFrameRate: frameRate,
-            }
+              mandatory: autoThrottling ? ({
+                  minWidth: 320,
+                  minHeight: 180,
+                  maxWidth: 1920,
+                  maxHeight: 1080,
+                  maxFrameRate: kMaxFrameRate,
+                  enableAutoThrottling: true
+              }) : ({
+                  minWidth: 1920,
+                  minHeight: 1080,
+                  maxWidth: 1920,
+                  maxHeight: 1080,
+                  maxFrameRate: kMaxFrameRate,
+              })
           }
         },
-        function startStreamingTestPatterns(captureStream) {
-          chrome.test.assertTrue(!!captureStream);
+        captureStream => {
+          if (!captureStream) {
+            chrome.test.fail(chrome.runtime.lastError.message || 'null stream');
+            return;
+          }
+
           chrome.cast.streaming.session.create(
               captureStream.getAudioTracks()[0],
               captureStream.getVideoTracks()[0],
-              function (audioId, videoId, udpId) {
+              (audioId, videoId, udpId) => {
                 chrome.cast.streaming.udpTransport.setDestination(
                     udpId, { address: "127.0.0.1", port: recvPort } );
-                var rtpStream = chrome.cast.streaming.rtpStream;
-                rtpStream.start(audioId,
-                                rtpStream.getSupportedParams(audioId)[0]);
-                var videoParams = rtpStream.getSupportedParams(videoId)[0];
-                videoParams.payload.clockRate = frameRate;
+                const rtpStream = chrome.cast.streaming.rtpStream;
+                rtpStream.onError.addListener(() => {
+                  chrome.test.fail('RTP stream error');
+                });
+                const audioParams = rtpStream.getSupportedParams(audioId)[0];
+                audioParams.payload.aesKey = aesKey;
+                audioParams.payload.aesIvMask = aesIvMask;
+                rtpStream.start(audioId, audioParams);
+                const videoParams = rtpStream.getSupportedParams(videoId)[0];
+                videoParams.payload.clockRate = kMaxFrameRate;
+                videoParams.payload.aesKey = aesKey;
+                videoParams.payload.aesIvMask = aesIvMask;
                 rtpStream.start(videoId, videoParams);
-                setTimeout(function () {
+                setTimeout(() => {
                   chrome.test.succeed();
+
                   rtpStream.stop(audioId);
                   rtpStream.stop(videoId);
-                }, 20000);  // 20 seconds
+                  rtpStream.destroy(audioId);
+                  rtpStream.destroy(videoId);
+
+                  const tracks = captureStream.getTracks();
+                  for (let i = 0; i < tracks.length; ++i) {
+                    tracks[i].stop();
+                  }
+                  chrome.test.assertFalse(captureStream.active);
+                }, 15000);  // 15 seconds
               });
         });
   }
 ]);