Adding more detailed UMA histogram for detection of output audio glitches.

BUG=NONE
TEST=Manual test of WebRTC clients under heavy load.
R=asvitkine@chromium.org, tommi@chromium.org

Review URL: https://codereview.chromium.org/534533002

Cr-Commit-Position: refs/heads/master@{#293099}

content/browser/renderer_host/media/audio_sync_reader.cc

@@ -9,12 +9,32 @@
 #include "base/command_line.h"
 #include "base/memory/shared_memory.h"
 #include "base/metrics/histogram.h"
+#include "base/strings/stringprintf.h"
+#include "content/browser/renderer_host/media/media_stream_manager.h"
 #include "content/public/common/content_switches.h"
 #include "media/audio/audio_buffers_state.h"
 #include "media/audio/audio_parameters.h"
 
 using media::AudioBus;
 
+namespace {
+
+// Used to log if any audio glitches have been detected during an audio session.
+// Elements in this enum should not be added, deleted or rearranged.
+enum AudioGlitchResult {
+  AUDIO_RENDERER_NO_AUDIO_GLITCHES = 0,
+  AUDIO_RENDERER_AUDIO_GLITCHES = 1,
+  AUDIO_RENDERER_AUDIO_GLITCHES_MAX = AUDIO_RENDERER_AUDIO_GLITCHES
+};
+
+void LogAudioGlitchResult(AudioGlitchResult result) {
+  UMA_HISTOGRAM_ENUMERATION("Media.AudioRendererAudioGlitches",
+                            result,
+                            AUDIO_RENDERER_AUDIO_GLITCHES_MAX + 1);
+}
+
+}  // namespace
+
 namespace content {
 
 AudioSyncReader::AudioSyncReader(base::SharedMemory* shared_memory,
@@ -47,6 +67,18 @@ AudioSyncReader::~AudioSyncReader() {
       100.0 * renderer_missed_callback_count_ / renderer_callback_count_;
   UMA_HISTOGRAM_PERCENTAGE(
       "Media.AudioRendererMissedDeadline", percentage_missed);
+
+  // Add more detailed information regarding detected audio glitches where
+  // a non-zero value of |renderer_missed_callback_count_| is added to the
+  // AUDIO_RENDERER_AUDIO_GLITCHES bin.
+  renderer_missed_callback_count_ > 0 ?
+      LogAudioGlitchResult(AUDIO_RENDERER_AUDIO_GLITCHES) :
+      LogAudioGlitchResult(AUDIO_RENDERER_NO_AUDIO_GLITCHES);
+  std::string log_string = base::StringPrintf(
+      "ASR: number of detected audio glitches=%ld",
+      renderer_missed_callback_count_);
+  MediaStreamManager::SendMessageToNativeLog(log_string);
+  DVLOG(1) << log_string;
 }
 
 // media::AudioOutputController::SyncReader implementations.

tools/metrics/histograms/histograms.xml

@@ -11067,6 +11067,14 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Media.AudioRendererAudioGlitches" enum="AudioGlitchResult">
+  <owner>henrika@chromium.org</owner>
+  <summary>
+    Captures if render-side audio glitches are detected or not. Sampled when a
+    low-latency output audio stream is destructed.
+  </summary>
+</histogram>
+
 <histogram name="Media.AudioRendererEvents" enum="AudioRendererEvents">
   <owner>scherkus@chromium.org</owner>
   <summary>Captures statistics for various AudioRendererImpl events.</summary>
@@ -37779,6 +37787,11 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="8" label="k1920"/>
 </enum>
 
+<enum name="AudioGlitchResult" type="int">
+  <int value="0" label="No audio glitches"/>
+  <int value="1" label="Audio glitches"/>
+</enum>
+
 <enum name="AudioInputSilenceReport" type="int">
   <int value="0" label="No measurement"/>
   <int value="1" label="Only audio"/>