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

content/test/data/media/webrtc_test_audio.js

Index: content/test/data/media/webrtc_test_audio.js
diff --git a/content/test/data/media/webrtc_test_audio.js b/content/test/data/media/webrtc_test_audio.js
index b9785bf5fbe88b670d96ecd3a73c2ef3200b1270..81fdec3ee530f7b241bf13ed8023fa1abff16887 100644
--- a/content/test/data/media/webrtc_test_audio.js
+++ b/content/test/data/media/webrtc_test_audio.js
@@ -7,6 +7,33 @@
 // 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,
@@ -34,15 +61,19 @@ function gatherAudioLevelSamples(peerConnection, numSamples, frequency,
   }, 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)
@@ -69,12 +100,15 @@ function verifyAudioIsPlaying(samples, beLenient) {
         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);