Web Audio: record autoplay status when an AudioContext is destroyed.

third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp

Index: third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp b/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
index cb83b9a35728164a9ca67af4e53409db1ed868a5..77fd418146e86f6c285da01900a4411e82ff1ea9 100644
--- a/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
@@ -107,6 +107,7 @@ BaseAudioContext::BaseAudioContext(Document* document)
   if (document->settings() &&
       document->settings()->mediaPlaybackRequiresUserGesture() &&
       document->frame() && document->frame()->isCrossOriginSubframe()) {
+    m_autoplayStatus = AutoplayStatus::AutoplayStatusFailed;
     m_userGestureRequired = true;
   }
 
@@ -144,6 +145,8 @@ BaseAudioContext::~BaseAudioContext() {
   DCHECK(!m_finishedSourceHandlers.size());
   DCHECK(!m_isResolvingResumePromises);
   DCHECK(!m_resumeResolvers.size());
+
+  recordAutoplayStatus();

[Raymond Toy, 2016/10/10 17:05:10]

I think if the user closes a tab, everything goes away, without necessarily
calling the destructor.  Is that ok for recording the status?

[mlamouri (slow - plz ping), 2016/10/10 18:44:40]

I guess if the object is marked as GCFinalized, it should call the dtor. At
least according to the doc. I wonder if there are downsides with this or if
recording in contextDestroyed would work most of the time.

+haraken@ to give some guidance.

 }
 
 void BaseAudioContext::initialize() {
@@ -196,6 +199,7 @@ void BaseAudioContext::contextDestroyed() {
 }
 
 bool BaseAudioContext::hasPendingActivity() const {
+  LOG(INFO) << "hasPendingActivity() => " << !m_isCleared;

[Raymond Toy, 2016/10/10 17:05:10]

Do you really want this log?  Just asking.

[mlamouri (slow - plz ping), 2016/10/10 18:44:40]

No :)

   // There's no pending activity if the audio context has been cleared.
   return !m_isCleared;
 }
@@ -553,6 +557,15 @@ PeriodicWave* BaseAudioContext::periodicWave(int type) {
   }
 }
 
+void BaseAudioContext::maybeRecordStartAttempt() {
+  if (!m_userGestureRequired || !UserGestureIndicator::processingUserGesture())
+    return;
+
+  DCHECK(!m_autoplayStatus.has_value() ||
+         m_autoplayStatus != AutoplayStatus::AutoplayStatusSucceeded);
+  m_autoplayStatus = AutoplayStatus::AutoplayStatusFailedWithStart;
+}
+
 String BaseAudioContext::state() const {
   // These strings had better match the strings for AudioContextState in
   // AudioContext.idl.
@@ -775,8 +788,12 @@ void BaseAudioContext::maybeUnlockUserGesture() {
   if (!m_userGestureRequired || !UserGestureIndicator::processingUserGesture())
     return;
 
+  DCHECK(!m_autoplayStatus.has_value() ||
+         m_autoplayStatus != AutoplayStatus::AutoplayStatusSucceeded);
+
   UserGestureIndicator::utilizeUserGesture();
   m_userGestureRequired = false;
+  m_autoplayStatus = AutoplayStatus::AutoplayStatusSucceeded;
 }
 
 bool BaseAudioContext::isAllowedToStart() const {
@@ -807,6 +824,18 @@ void BaseAudioContext::rejectPendingResolvers() {
   rejectPendingDecodeAudioDataResolvers();
 }
 
+void BaseAudioContext::recordAutoplayStatus() {
+  if (!m_autoplayStatus.has_value())
+    return;
+
+  DEFINE_STATIC_LOCAL(
+      EnumerationHistogram, autoplayHistogram,
+      ("WebAudio.Autoplay.CrossOrigin", AutoplayStatus::AutoplayStatusCount));
+  autoplayHistogram.count(m_autoplayStatus.value());
+
+  m_autoplayStatus.reset();
+}
+
 const AtomicString& BaseAudioContext::interfaceName() const {
   return EventTargetNames::AudioContext;
 }