Add AudioInputControllerCaptureStartupSuccess UMA

media/audio/audio_input_controller.cc

Index: media/audio/audio_input_controller.cc
diff --git a/media/audio/audio_input_controller.cc b/media/audio/audio_input_controller.cc
index 4cf948b1ad318d7b0b65c2e61c5fbb2ea07e2d2f..c03a83b05917a8f1bfaa65b2b6e6083e70672ec2 100644
--- a/media/audio/audio_input_controller.cc
+++ b/media/audio/audio_input_controller.cc
@@ -212,12 +212,12 @@ void AudioInputController::DoCreateForStream(
   enable_nodata_timer = true;

[henrika (OOO until Aug 14), 2014/05/09 13:15:07]

When was this guy enabled again? I had disabled it to avoid issues on Mac and
now it is on again. What has happened?

[tommi (sloooow) - chröme, 2014/05/09 13:40:43]

This was changed about a month ago:
https://codereview.chromium.org/229573003

 
   if (enable_nodata_timer) {
-    // Create the data timer which will call DoCheckForNoData(). The timer
+    // Create the data timer which will call FirstCheckForNoData(). The timer
     // is started in DoRecord() and restarted in each DoCheckForNoData()
     // callback.
     no_data_timer_.reset(new base::Timer(
         FROM_HERE, base::TimeDelta::FromSeconds(kTimerInitialIntervalSeconds),
-        base::Bind(&AudioInputController::DoCheckForNoData,
+        base::Bind(&AudioInputController::FirstCheckForNoData,
                    base::Unretained(this)), false));
   } else {
     DVLOG(1) << "Disabled: timer check for no data.";
@@ -247,7 +247,7 @@ void AudioInputController::DoRecord() {
 
   if (no_data_timer_) {
     // Start the data timer. Once |kTimerResetIntervalSeconds| have passed,
-    // a callback to DoCheckForNoData() is made.
+    // a callback to FirstCheckForNoData() is made.
     no_data_timer_->Reset();
   }
 
@@ -318,6 +318,13 @@ void AudioInputController::DoSetAutomaticGainControl(bool enabled) {
   stream_->SetAutomaticGainControl(enabled);
 }
 
+void AudioInputController::FirstCheckForNoData() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  UMA_HISTOGRAM_BOOLEAN("Media.AudioInputControllerCaptureStartupSuccess",
+                        GetDataIsActive());

[tommi (sloooow) - chröme, 2014/05/09 13:40:43]

How do you know that SetDataIsActive has been called at this point?

[no longer working on chromium, 2014/05/09 13:48:22]

OnData() calls SetDataIsActive(true) when getting recording data. So if OnData()
is called before the check, GetDataIsActive() return a true, which means the
capture starts successfully.
If GetDataIsActive() is a false, that means we do not get any OnData() after the
stream has started.

Let me know if I misunderstand things here.

[tommi (sloooow) - chröme, 2014/05/09 13:56:21]

Yeah I know how it's supposed to work but I'm wondering how we make sure we
don't report false positives.
If we get this callback before OnData is called - but OnData gets called
immediately after, then we will have incorrectly recorded that we capture is not
working.  I'm basically asking, is that not possible? and if so, how do we
guarantee that it is not possible.

[tommi (sloooow) - chröme, 2014/05/09 14:46:15]

Actually, I think this is fine.  The 5 second period should be more than enough
to check this, so lgtm.

One more thing to think about down the line.  If we start seeing that
GetDataIsActive returns 0 in our logs, what would be the next steps to look at? 
Also, see one request below.

+  DoCheckForNoData();
+}
+
 void AudioInputController::DoCheckForNoData() {
   DCHECK(task_runner_->BelongsToCurrentThread());