Tighten up webrtc audio tests.

content/test/data/media/peerconnection-call.html

Index: content/test/data/media/peerconnection-call.html
diff --git a/content/test/data/media/peerconnection-call.html b/content/test/data/media/peerconnection-call.html
index 29a23b8f9151bde9b034f3b21a6c4eb347144d21..85b0ea636a551da6c3ee9555854db2aa1a3fed50 100644
--- a/content/test/data/media/peerconnection-call.html
+++ b/content/test/data/media/peerconnection-call.html
@@ -291,8 +291,8 @@
     // Wait until we have gathered samples and can conclude if audio is playing.
     addExpectedEvent();
     var onCallEstablished = function() {
-      gatherAudioLevelSamples(gSecondConnection, 300, 100,
-                              function(samples) {
+      // Gather 10 samples per second for 4 seconds.
+      gatherAudioLevelSamples(gSecondConnection, 40, 10, function(samples) {

[phoglund_chromium, 2014/03/28 13:55:26]

Ok, I doubled the beep frequency and halved the gathering times (4 secs -> 2
secs).

         verifyAudioIsPlaying(samples);
         eventOccured();
       });
@@ -312,7 +312,7 @@
       enableRemoteAudio(gSecondConnection, false);
 
       setTimeout(function() {
-        gatherAudioLevelSamples(gSecondConnection, 200, 100, function(samples) {
+        gatherAudioLevelSamples(gSecondConnection, 20, 10, function(samples) {
           verifyIsSilent(samples);
           reportTestSuccess();
         });
@@ -331,7 +331,7 @@
       }, 500);
 
       setTimeout(function() {
-        gatherAudioLevelSamples(gSecondConnection, 200, 100, function(samples) {
+        gatherAudioLevelSamples(gSecondConnection, 40, 10, function(samples) {

[perkj_chrome, 2014/03/28 13:29:17]

why is this 40 samples to check for playing while you can decide that its not
playing in just 20? 

Do these test really need to run for 4s? How about sending the beeps more
frequently? 

[phoglund_chromium, 2014/03/28 13:55:26]

We need more of a safety margin when determining if we are playing. If we sample
over 4 seconds we can expect 4 peaks, but I can imagine we'll only see 3 in some
cases because the sampling lines up badly or we are running on a slow machine.
If we see only zeroes for two seconds we can be pretty sure nothing is coming.

           verifyAudioIsPlaying(samples);
           reportTestSuccess();
         });