Added logging of average power levels to AudioOutputController.

media/audio/audio_output_controller.cc

Index: media/audio/audio_output_controller.cc
diff --git a/media/audio/audio_output_controller.cc b/media/audio/audio_output_controller.cc
index fdca8112f14caba8fe3da63ef0d365914576dfd8..7d6dbee8cafa3d27cdb8cd25efe89075bc710870 100644
--- a/media/audio/audio_output_controller.cc
+++ b/media/audio/audio_output_controller.cc
@@ -22,6 +22,10 @@
 using base::TimeDelta;
 
 namespace media {
+namespace {
+// Time in seconds between two successive measurements of audio power levels.
+constexpr int kPowerMonitorLogIntervalSeconds = 15;
+}  // namespace
 
 AudioOutputController::AudioOutputController(
     AudioManager* audio_manager,
@@ -165,6 +169,10 @@ void AudioOutputController::DoPlay() {
 
   state_ = kPlaying;
 
+  if (will_monitor_audio_levels()) {
+    last_audio_level_log_time_ = base::TimeTicks::Now();

[liberato (no reviews please), 2017/05/30 17:00:53]

i think that this will be default-constructed to 0, which should work fine for
the check @303.

[ossu-chromium, 2017/05/31 11:44:40]

Acknowledged.

[ossu-chromium, 2017/05/31 11:44:40]

It needs to be reset to something in DoPlay, and Now() seems as good a value as
any, to me.

[liberato (no reviews please), 2017/05/31 19:39:22]

ah -- i mis-read the diff.  yeah, you're right.

anyway, one can drop the {} for single-line if, here and elsewhere.

+  }
+
   stream_->Start(this);
 
   // For UMA tracking purposes, start the wedge detection timer.  This allows us
@@ -288,9 +296,22 @@ int AudioOutputController::OnMoreData(base::TimeDelta delay,
             std::move(copy), reference_time));
   }
 
-  if (will_monitor_audio_levels())
+  if (will_monitor_audio_levels()) {
     power_monitor_.Scan(*dest, frames);
 
+    const auto now = base::TimeTicks::Now();
+    if ((now - last_audio_level_log_time_).InSeconds() >
+        kPowerMonitorLogIntervalSeconds) {
+      std::pair<float, bool> power_and_clip =
+          power_monitor_.ReadCurrentPowerAndClip();
+
+      handler_->OnLog(
+          base::StringPrintf("AOC::OnMoreData: average audio level=%.2f dBFS",
+                             power_and_clip.first));
+      last_audio_level_log_time_ = now;
+    }
+  }
+
   return frames;
 }