Autoplay muted video when visible and pause when invisible

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 394 matching lines @@
       m_displayMode(Unknown),
       m_officialPlaybackPosition(0),
       m_officialPlaybackPositionNeedsUpdate(true),
       m_fragmentEndTime(std::numeric_limits<double>::quiet_NaN()),
       m_pendingActionFlags(0),
       m_lockedPendingUserGesture(false),
       m_lockedPendingUserGestureIfCrossOriginExperimentEnabled(true),
       m_playing(false),
       m_shouldDelayLoadEvent(false),
       m_haveFiredLoadedData(false),
-      m_autoplaying(true),
+      m_canAutoplay(true),
       m_muted(false),
       m_paused(true),
       m_seeking(false),
       m_sentStalledEvent(false),
       m_ignorePreloadNone(false),
       m_textTracksVisible(false),
       m_shouldPerformAutomaticTrackSelection(true),
       m_tracksAreReady(true),
       m_processingPreferenceChange(false),
       m_playingRemotely(false),
@@ skipping 430 matching lines @@
     // This is where that change would have an effect, and it is measured to
     // verify the assumption that it's a very rare situation.
     UseCounter::count(document(),
                       UseCounter::HTMLMediaElementLoadNetworkEmptyNotPaused);
   }
 
   // 7 - Set the playbackRate attribute to the value of the defaultPlaybackRate
   // attribute.
   setPlaybackRate(defaultPlaybackRate());
 
-  // 8 - Set the error attribute to null and the autoplaying flag to true.
+  // 8 - Set the error attribute to null and the can autoplay flag to true.
   m_error = nullptr;
-  m_autoplaying = true;
+  m_canAutoplay = true;
 
   // 9 - Invoke the media element's resource selection algorithm.
   invokeResourceSelectionAlgorithm();
 
   // 10 - Note: Playback of any previously playing media resource for this
   // element stops.
 }
 
 void HTMLMediaElement::invokeResourceSelectionAlgorithm() {
   BLINK_MEDIA_LOG << "invokeResourceSelectionAlgorithm(" << (void*)this << ")";
@@ skipping 865 matching lines @@
             m_autoplayVisibilityObserver = new ElementVisibilityObserver(
                 this,
                 WTF::bind(&HTMLMediaElement::onVisibilityChangedForAutoplay,
                           wrapWeakPersistent(this)));
             m_autoplayVisibilityObserver->start();
           }
         } else {
           m_paused = false;
           scheduleEvent(EventTypeNames::play);
           scheduleNotifyPlaying();
-          m_autoplaying = false;
+          m_canAutoplay = false;
         }
       } else {
         m_autoplayUmaHelper->recordCrossOriginAutoplayResult(
             CrossOriginAutoplayResult::AutoplayBlocked);
       }
     }
 
     scheduleEvent(EventTypeNames::canplaythrough);
 
     shouldUpdateDisplayState = true;
@@ skipping 326 matching lines @@
   return endedPlayback() && getDirectionOfPlayback() == Forward;
 }
 
 bool HTMLMediaElement::autoplay() const {
   return fastHasAttribute(autoplayAttr);
 }
 
 bool HTMLMediaElement::shouldAutoplay() {
   if (document().isSandboxed(SandboxAutomaticFeatures))
     return false;
-  return m_autoplaying && m_paused && autoplay();
+  return m_canAutoplay && m_paused && autoplay();
 }
 
 String HTMLMediaElement::preload() const {
   return preloadTypeToString(preloadType());
 }
 
 void HTMLMediaElement::setPreload(const AtomicString& preload) {
   BLINK_MEDIA_LOG << "setPreload(" << (void*)this << ", " << preload << ")";
   setAttribute(preloadAttr, preload);
 }
@@ skipping 128 matching lines @@
   } else {
     m_autoplayUmaHelper->recordCrossOriginAutoplayResult(
         CrossOriginAutoplayResult::PlayedWithGesture);
     UserGestureIndicator::utilizeUserGesture();
     unlockUserGesture();
   }
 
   if (m_error && m_error->code() == MediaError::kMediaErrSrcNotSupported)
     return NotSupportedError;
 
+  if (m_autoplayVisibilityObserver) {
+    m_autoplayVisibilityObserver->stop();
+    m_autoplayVisibilityObserver = nullptr;
+  }
+
   playInternal();
 
   return nullptr;
 }
 
 void HTMLMediaElement::playInternal() {
   BLINK_MEDIA_LOG << "playInternal(" << (void*)this << ")";
 
   // Always return the buffering strategy to normal when not paused,
   // regardless of the cause. (In contrast with aggressive buffering which is
@@ skipping 17 matching lines @@
     scheduleEvent(EventTypeNames::play);
 
     if (m_readyState <= kHaveCurrentData)
       scheduleEvent(EventTypeNames::waiting);
     else if (m_readyState >= kHaveFutureData)
       scheduleNotifyPlaying();
   } else if (m_readyState >= kHaveFutureData) {
     scheduleResolvePlayPromises();
   }
 
-  m_autoplaying = false;
+  m_canAutoplay = false;
 
   setIgnorePreloadNone();
   updatePlayState();
 }
 
 void HTMLMediaElement::pause() {
   BLINK_MEDIA_LOG << "pause(" << (void*)this << ")";
 
   // Only buffer aggressively on a user-initiated pause. Other types of pauses
   // (which go directly to pauseInternal()) should not cause this behavior.
   if (webMediaPlayer() && UserGestureIndicator::utilizeUserGesture())
     webMediaPlayer()->setBufferingStrategy(
         WebMediaPlayer::BufferingStrategy::Aggressive);
 
+  if (m_autoplayVisibilityObserver) {
+    m_autoplayVisibilityObserver->stop();
+    m_autoplayVisibilityObserver = nullptr;
+  }
+
   pauseInternal();
 }
 
 void HTMLMediaElement::pauseInternal() {
   BLINK_MEDIA_LOG << "pauseInternal(" << (void*)this << ")";
 
   if (m_networkState == kNetworkEmpty)
     invokeResourceSelectionAlgorithm();
 
-  m_autoplaying = false;
+  m_canAutoplay = false;
 
   if (!m_paused) {
     m_paused = true;
     scheduleTimeupdateEvent(false);
     scheduleEvent(EventTypeNames::pause);
 
     // Force an update to official playback position. Automatic updates from
     // currentPlaybackPosition() will be blocked while m_paused = true. This
     // blocking is desired while paused, but its good to update it one final
     // time to accurately reflect movie time at the moment we paused.
@@ skipping 1672 matching lines @@
                         ("Media.Controls.Show.Video", MediaControlsShowMax));
     return histogram;
   }
 
   DEFINE_STATIC_LOCAL(EnumerationHistogram, histogram,
                       ("Media.Controls.Show.Audio", MediaControlsShowMax));
   return histogram;
 }
 
 void HTMLMediaElement::onVisibilityChangedForAutoplay(bool isVisible) {
-  if (!isVisible)
+  if (!isVisible) {
+    if (m_canAutoplay && autoplay()) {

[mlamouri (slow - plz ping), 2017/02/14 20:59:02]

Would it make sense to add a DCHECK(isAutoplayMuted())?

[Zhiqiang Zhang (Slow), 2017/02/14 21:47:31]

Hmm, it might hit this DCHECK when the page calls `video.autoplay = false` after
it starts autoplaying. Currently I think we do nothing when unsetting the
attribute.

+      pauseInternal();
+      m_canAutoplay = true;
+    }
     return;
+  }
 
   if (shouldAutoplay()) {
     m_paused = false;
     scheduleEvent(EventTypeNames::play);
     scheduleNotifyPlaying();
-    m_autoplaying = false;
 
     updatePlayState();
   }
-
-  // TODO(zqzhang): There's still flaky leak if onVisibilityChangedForAutoplay()
-  // is never called.  The leak comes from either ElementVisibilityObserver or
-  // IntersectionObserver. Should keep an eye on it.  See
-  // https://crbug.com/627539
-  m_autoplayVisibilityObserver->stop();
-  m_autoplayVisibilityObserver = nullptr;
 }
 
 void HTMLMediaElement::clearWeakMembers(Visitor* visitor) {
   if (!ThreadHeap::isHeapObjectAlive(m_audioSourceNode)) {
     getAudioSourceProvider().setClient(nullptr);
     m_audioSourceNode = nullptr;
   }
 }
 
 void HTMLMediaElement::AudioSourceProviderImpl::wrap(
@@ skipping 94 matching lines @@
       kMostlyFillViewportBecomeStableSeconds, BLINK_FROM_HERE);
 }
 
 void HTMLMediaElement::viewportFillDebouncerTimerFired(TimerBase*) {
   m_mostlyFillingViewport = true;
   if (m_webMediaPlayer)
     m_webMediaPlayer->becameDominantVisibleContent(m_mostlyFillingViewport);
 }
 
 }  // namespace blink