Stop source and fire MediaStreamTrack ended event if missing audio input callbacks are detected.

media/audio/mac/audio_low_latency_input_mac.cc

Index: media/audio/mac/audio_low_latency_input_mac.cc
diff --git a/media/audio/mac/audio_low_latency_input_mac.cc b/media/audio/mac/audio_low_latency_input_mac.cc
index 15640a57ca94816cdef601122bef988982cf6150..e7e4f78e0e16911e703e6355d7ce6ced6e3424fe 100644
--- a/media/audio/mac/audio_low_latency_input_mac.cc
+++ b/media/audio/mac/audio_low_latency_input_mac.cc
@@ -36,9 +36,9 @@ const int kMaxErrorTimeoutInSeconds = 1;
 // stream back to life.
 const int kCheckInputIsAliveTimeInSeconds = 5;
 
-// Number of restart indications required to actually trigger a restart
-// attempt.
-const int kNumberOfIndicationsToTriggerRestart = 1;
+// Number of restart indications required to trigger a restart after a
+// successful start.
+const int kIndicationsToTriggerRestartAfterSuccessfulStart = 2;
 
 // Max number of times we try to restart a stream when it has been categorized
 // as dead. Note that we can do many restarts during an audio session and this
@@ -1272,18 +1272,21 @@ void AUAudioInputStream::CheckIfInputStreamIsAlive() {
   }
 
   // Restart the audio stream if two conditions are met. First, the number of
-  // restart indicators must be larger than a threshold, and secondly, only a
+  // restart indicators must reach a threshold, and secondly, only a
   // fixed number of restart attempts is allowed.
   // Note that, the threshold is different depending on if the stream is seen
   // as dead directly at the first call to Start() (i.e. it has never started)
   // or if the stream has started OK at least once but then stopped for some
   // reason (e.g by placing the device in sleep mode). One restart indication
   // is sufficient for the first case (threshold is zero), while a larger value
-  // (threshold > 0) is required for the second case to avoid false alarms when
+  // (threshold > 1) is required for the second case to avoid false alarms when
   // e.g. resuming from a suspended state.
-  const size_t restart_threshold =
-      GetInputCallbackIsActive() ? kNumberOfIndicationsToTriggerRestart : 0;
-  if (number_of_restart_indications_ > restart_threshold &&
+  const size_t indications_to_trigger_restart =
+      GetInputCallbackIsActive()
+          ? kIndicationsToTriggerRestartAfterSuccessfulStart
+          : 1;
+  DCHECK_LE(number_of_restart_indications_, indications_to_trigger_restart);
+  if (number_of_restart_indications_ == indications_to_trigger_restart &&

[ossu-chromium, 2017/05/22 11:27:35]

So, this is functionally equivalent but rephrased to be a bit simpler to read?

[Henrik Grunell, 2017/05/22 15:04:54]

Yes, exactly. I hope you agree it is. :o

       number_of_restart_attempts_ < kMaxNumberOfRestartAttempts) {
     SetInputCallbackIsActive(false);
     ++total_number_of_restart_attempts_;