Adding lenient mode to 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 76ca1b3e64eb2af8da28d511876db69142b7c034..0cf4ac7f62a000caa7077de79c34e4357b72df40 100644
--- a/content/test/data/media/webrtc_test_audio.js
+++ b/content/test/data/media/webrtc_test_audio.js
@@ -29,13 +29,15 @@ function gatherAudioLevelSamples(peerConnection, numSamples, frequency,
 // 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). We are quite
-// generous in what we consider to be a peak since Android devices in particular
-// seem to be flake-prone (they often don't reach anywhere near the max level
-// for some reason).
-function verifyAudioIsPlaying(samples) {
+// (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) {
   var numPeaks = 0;
-  var threshold = MAX_AUDIO_OUTPUT_ENERGY * 0.6;
+  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
@@ -48,9 +50,14 @@ function verifyAudioIsPlaying(samples) {
 
   console.log('Number of peaks identified: ' + numPeaks);
 
-  if (numPeaks < 2)
-    failTest('Expected to see at least two peaks in audio signal, got ' +
-        numPeaks + '. Dumping samples for analysis: "' + samples + '"');
+  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.