Adding Media.InputStreamDuration to UMA histograms for low-latency input audio streams

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 72fb83b49ae26a4f4f57761bbda7ef449e96c801..d4ccd2eddd4bb17310c4997fdd167a30d1dc3bf7 100644
--- a/media/audio/audio_input_controller.cc
+++ b/media/audio/audio_input_controller.cc
@@ -263,6 +263,7 @@ void AudioInputController::DoCreateForLowLatency(AudioManager* audio_manager,
     log_silence_state_ = true;
 #endif
 
+  low_latency_create_time_ = base::TimeTicks::Now();
   DoCreate(audio_manager, params, device_id);
 }
 
@@ -347,8 +348,19 @@ void AudioInputController::DoClose() {
   if (state_ == CLOSED)
     return;
 
-  if (handler_)
-    handler_->OnLog(this, "AIC::DoClose");
+  // If this is a low-latency stream, log the total duration (since DoCreate)
+  // and add it to a UMA histogram.
+  if (!low_latency_create_time_.is_null()) {
+    base::TimeDelta duration =
+        base::TimeTicks::Now() - low_latency_create_time_;
+    UMA_HISTOGRAM_LONG_TIMES("Media.InputStreamDuration", duration);

[Henrik Grunell, 2014/09/04 06:32:17]

I think it should be called Media.AudioInputController.InputStreamDuration.

[henrika (OOO until Aug 14), 2014/09/04 12:27:37]

Discussed off-line. Henrik G is OK with excluding the AudioInputController part.

+    if (handler_) {
+      std::ostringstream oss;

[tommi (sloooow) - chröme, 2014/09/03 13:50:03]

use StringPrintf (stringstream should only be used for logging)

[henrika (OOO until Aug 14), 2014/09/04 12:27:37]

I tried to use it but was not able to come up with a nice way to make it accept
the int64 on all platforms. Any idea which format specifier I could use?

May I ask why stringstream is not OK here?

[henrika (OOO until Aug 14), 2014/09/04 12:54:13]

Anyhow, fixed now ;-)

[tommi (sloooow) - chröme, 2014/09/04 16:53:21]

It's because of the style guide.  stringstream is OK for logging only and from
discussing this with others, the interpretation is that logging is debug logging
(i.e. [D]LOG etc) and this falls outside of that since it could easily start
creeping into non-logging code such as functions etc.

+      oss << "AIC::DoClose: stream duration="
+          << duration.InSeconds() << " seconds";
+      handler_->OnLog(this, oss.str());
+    }
+  }
 
   // Delete the timer on the same thread that created it.
   no_data_timer_.reset();