Adding local stream mute tests, tightening up WebRTC audio tests.

content/test/data/media/webrtc_test_audio.js

 // Copyright 2013 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.
 
 // Audio test utilities.
 
 // GetStats reports audio output energy in the [0, 32768] range.
 var MAX_AUDIO_OUTPUT_ENERGY = 32768;
 
+// Queries WebRTC stats on |peerConnection| to find out whether audio is playing
+// on the connection. Note this does not necessarily mean the audio is actually
+// playing out (for instance if there's a bug in the WebRTC web media player).
+// If |beLenient| is true, we assume we're on a slow and unreliable bot and that
+// we should do a minimum of checking.
+function ensureAudioPlaying(peerConnection, beLenient) {
+  addExpectedEvent();
+
+  // Gather 50 samples per second for 2 seconds.
+  gatherAudioLevelSamples(peerConnection, 100, 50, function(samples) {
+    identifyFakeDeviceSignal_(samples, beLenient);
+    eventOccured();
+  });
+}
+
+// Queries WebRTC stats on |peerConnection| to find out whether audio is muted
+// on the connection.
+function ensureSilence(peerConnection) {
+  addExpectedEvent();
+  setTimeout(function() {
+    gatherAudioLevelSamples(peerConnection, 100, 50, function(samples) {
+      identifySilence_(samples);
+      eventOccured();
+    });
+  }, 500);
+}
+
 // Gathers |numSamples| samples at |frequency| number of times per second and
 // calls back |callback| with an array with numbers in the [0, 32768] range.
 function gatherAudioLevelSamples(peerConnection, numSamples, frequency,
                                  callback) {
   console.log('Gathering ' + numSamples + ' audio samples...');
   var audioLevelSamples = []
   var gatherSamples = setInterval(function() {
     peerConnection.getStats(function(response) {
       audioOutputLevels = getAudioLevelFromStats_(response);
       if (audioOutputLevels.length == 0) {
         // The call probably isn't up yet.
         return;
       }
 
       // If more than one audio level is reported we get confused.
       assertEquals(1, audioOutputLevels.length);
       audioLevelSamples.push(audioOutputLevels[0]);
 
       if (audioLevelSamples.length == numSamples) {
         console.log('Gathered all samples.');
         clearInterval(gatherSamples);
         callback(audioLevelSamples);
       }
     });
   }, 1000 / frequency);
 }
 
-// Tries to identify the beep-every-half-second signal generated by the fake
-// audio device in media/video/capture/fake_video_capture_device.cc. Fails the
-// test if we can't see a signal. The samples should have been gathered over at
-// least two seconds since we expect to see at least three "peaks" in there
-// (we should see either 3 or 4 depending on how things line up).
-//
-// If |beLenient| is specified, we assume we're running on a slow device or
-// or under TSAN, and relax the checks quite a bit.
-function verifyAudioIsPlaying(samples, beLenient) {
+/**
+* Tries to identify the beep-every-half-second signal generated by the fake
+* audio device in media/video/capture/fake_video_capture_device.cc. Fails the
+* test if we can't see a signal. The samples should have been gathered over at
+* least two seconds since we expect to see at least three "peaks" in there
+* (we should see either 3 or 4 depending on how things line up).
+*
+* If |beLenient| is specified, we assume we're running on a slow device or
+* or under TSAN, and relax the checks quite a bit.
+*
+* @private
+*/
+function identifyFakeDeviceSignal_(samples, beLenient) {
   var numPeaks = 0;
   var threshold = MAX_AUDIO_OUTPUT_ENERGY * 0.7;
   if (beLenient)
     threshold = MAX_AUDIO_OUTPUT_ENERGY * 0.6;
   var currentlyOverThreshold = false;
 
   // Detect when we have been been over the threshold and is going back again
   // (i.e. count peaks). We should see about one peak per second.
   for (var i = 0; i < samples.length; ++i) {
     if (currentlyOverThreshold && samples[i] < threshold)
       numPeaks++;
     currentlyOverThreshold = samples[i] >= threshold;
   }
 
   console.log('Number of peaks identified: ' + numPeaks);
 
   var expectedPeaks = 2;
   if (beLenient)
     expectedPeaks = 1;
 
   if (numPeaks < expectedPeaks)
     failTest('Expected to see at least ' + expectedPeaks + ' peak(s) in ' +
         'audio signal, got ' + numPeaks + '. Dumping samples for analysis: "' +
         samples + '"');
 }
 
-// If silent (like when muted), we should get very near zero audio level.
-function verifyIsSilent(samples) {
+/**
+ * @private
+ */
+function identifySilence_(samples) {
   var average = 0;
   for (var i = 0; i < samples.length; ++i)
     average += samples[i] / samples.length;
 
+  // If silent (like when muted), we should get very near zero audio level.
   console.log('Average audio level: ' + average);
   if (average > 500)
     failTest('Expected silence, but avg audio level was ' + average);
 }
 
 /**
  * @private
  */
 function getAudioLevelFromStats_(response) {
   var reports = response.result();
   var audioOutputLevels = [];
   for (var i = 0; i < reports.length; ++i) {
     var report = reports[i];
     if (report.names().indexOf('audioOutputLevel') != -1) {
       audioOutputLevels.push(report.stat('audioOutputLevel'));
     }
   }
   return audioOutputLevels;
 }