Start autoplay muted videos with autoplay attribute when they are visible.

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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 17 matching lines @@
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
 #include "bindings/core/v8/ScriptController.h"
 #include "bindings/core/v8/ScriptEventListener.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/HTMLNames.h"
 #include "core/css/MediaList.h"
 #include "core/dom/Attribute.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/ElementTraversal.h"
+#include "core/dom/ElementVisibilityObserver.h"
 #include "core/dom/Fullscreen.h"
 #include "core/dom/shadow/ShadowRoot.h"
 #include "core/events/Event.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/frame/UseCounter.h"
 #include "core/frame/csp/ContentSecurityPolicy.h"
 #include "core/html/HTMLMediaSource.h"
 #include "core/html/HTMLSourceElement.h"
@@ skipping 299 matching lines @@
         visitor->trace(m_element);
         Client::trace(visitor);
     }
 
 private:
     AutoplayHelperClientImpl(HTMLMediaElement* element) : m_element(element) {}
 
     Member<HTMLMediaElement> m_element;
 };
 
-
 void HTMLMediaElement::recordAutoplayMetric(AutoplayMetrics metric)
 {
     DEFINE_STATIC_LOCAL(EnumerationHistogram, autoplayHistogram, ("Blink.MediaElement.Autoplay", NumberOfAutoplayMetrics));
     autoplayHistogram.count(metric);
 }
 
 WebMimeRegistry::SupportsType HTMLMediaElement::supportsType(const ContentType& contentType)
 {
     DEFINE_STATIC_LOCAL(const String, codecs, ("codecs"));
 
@@ skipping 75 matching lines @@
     , m_inOverlayFullscreenVideo(false)
     , m_audioTracks(AudioTrackList::create(*this))
     , m_videoTracks(VideoTrackList::create(*this))
     , m_textTracks(nullptr)
     , m_playPromiseResolveTask(CancellableTaskFactory::create(this, &HTMLMediaElement::resolveScheduledPlayPromises))
     , m_playPromiseRejectTask(CancellableTaskFactory::create(this, &HTMLMediaElement::rejectScheduledPlayPromises))
     , m_audioSourceNode(nullptr)
     , m_autoplayHelperClient(AutoplayHelperClientImpl::create(this))
     , m_autoplayHelper(AutoplayExperimentHelper::create(m_autoplayHelperClient.get()))
     , m_remotePlaybackClient(nullptr)
+    , m_autoplayVisibilityObserver(nullptr)
 {
     ThreadState::current()->registerPreFinalizer(this);
 
     DVLOG(MEDIA_LOG_LEVEL) << "HTMLMediaElement(" << (void*)this << ")";
 
     // If any experiment is enabled, then we want to enable a user gesture by
     // default, otherwise the experiment does nothing.
     if ((document.settings() && document.settings()->mediaPlaybackRequiresUserGesture())
         || m_autoplayHelper->isExperimentEnabled()) {
         m_lockedPendingUserGesture = true;
@@ skipping 1171 matching lines @@
     if (m_readyState == HAVE_ENOUGH_DATA && oldState < HAVE_ENOUGH_DATA && tracksAreReady) {
         if (oldState <= HAVE_CURRENT_DATA) {
             scheduleEvent(EventTypeNames::canplay);
             if (isPotentiallyPlaying)
                 scheduleNotifyPlaying();
         }
 
         // Check for autoplay, and record metrics about it if needed.
         if (shouldAutoplay(RecordMetricsBehavior::DoRecord)) {
             recordAutoplaySourceMetric(AutoplaySourceAttribute);
+
             // If the autoplay experiment says that it's okay to play now,
             // then don't require a user gesture.
             m_autoplayHelper->becameReadyToPlay();
 
             if (!isGestureNeededForPlayback()) {
-                m_paused = false;
-                invalidateCachedTime();
-                scheduleEvent(EventTypeNames::play);
-                scheduleNotifyPlaying();
-                m_autoplaying = false;
+                if (muted() && RuntimeEnabledFeatures::autoplayMutedVideosEnabled()) {
+                    m_autoplayVisibilityObserver = new ElementVisibilityObserver(this, WTF::bind<bool>(&HTMLMediaElement::onVisibilityChangedForAutoplay, this));
+                    m_autoplayVisibilityObserver->start();
+                } else {
+                    m_paused = false;
+                    invalidateCachedTime();
+                    scheduleEvent(EventTypeNames::play);
+                    scheduleNotifyPlaying();
+                    m_autoplaying = false;
+                }
             }
         }
 
         scheduleEvent(EventTypeNames::canplaythrough);
 
         shouldUpdateDisplayState = true;
     }
 
     if (shouldUpdateDisplayState) {
         updateDisplayState();
@@ skipping 451 matching lines @@
 
     playInternal();
 
     return nullptr;
 }
 
 void HTMLMediaElement::playInternal()
 {
     DVLOG(MEDIA_LOG_LEVEL) << "playInternal(" << (void*)this << ")";
 
+    // Playing is about to start from script, no need to wait for visibility.
+    if (m_autoplayVisibilityObserver) {
+        m_autoplayVisibilityObserver->stop();
+        m_autoplayVisibilityObserver = nullptr;
+    }
+
     // Always return the buffering strategy to normal when not paused,
     // regardless of the cause. (In contrast with aggressive buffering which is
     // only enabled by pause(), not pauseInternal().)
     if (webMediaPlayer())
         webMediaPlayer()->setBufferingStrategy(WebMediaPlayer::BufferingStrategy::Normal);
 
     // 4.8.10.9. Playing the media resource
     if (m_networkState == NETWORK_EMPTY)
         invokeResourceSelectionAlgorithm();
 
@@ skipping 1500 matching lines @@
     visitor->trace(m_cueTimeline);
     visitor->trace(m_textTracks);
     visitor->trace(m_textTracksWhenResourceSelectionBegan);
     visitor->trace(m_playPromiseResolvers);
     visitor->trace(m_playPromiseResolveList);
     visitor->trace(m_playPromiseRejectList);
     visitor->trace(m_audioSourceProvider);
     visitor->trace(m_autoplayHelperClient);
     visitor->trace(m_autoplayHelper);
     visitor->trace(m_srcObject);
+    visitor->trace(m_autoplayVisibilityObserver);
     visitor->template registerWeakMembers<HTMLMediaElement, &HTMLMediaElement::clearWeakMembers>(this);
     Supplementable<HTMLMediaElement>::trace(visitor);
     HTMLElement::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 DEFINE_TRACE_WRAPPERS(HTMLMediaElement)
 {
     visitor->traceWrappers(m_videoTracks);
     visitor->traceWrappers(m_audioTracks);
@@ skipping 197 matching lines @@
 
     if (isHTMLVideoElement()) {
         videoHistogram.count(source);
         if (muted())
             mutedVideoHistogram.count(source);
     } else {
         audioHistogram.count(source);
     }
 }
 
+void HTMLMediaElement::onVisibilityChangedForAutoplay(bool isVisible)
+{
+    if (!isVisible)
+        return;
+
+    playInternal();
+
+    // The observation should have been stopped by the call to playInternal
+    DCHECK(!m_autoplayVisibilityObserver);
+}
+
 void HTMLMediaElement::clearWeakMembers(Visitor* visitor)
 {
     if (!ThreadHeap::isHeapObjectAlive(m_audioSourceNode)) {
         getAudioSourceProvider().setClient(nullptr);
         m_audioSourceNode = nullptr;
     }
 }
 
 void HTMLMediaElement::AudioSourceProviderImpl::wrap(WebAudioSourceProvider* provider)
 {
@@ skipping 97 matching lines @@
 
 IntRect HTMLMediaElement::AutoplayHelperClientImpl::absoluteBoundingBoxRect() const
 {
     IntRect result;
     if (LayoutObject* object = m_element->layoutObject())
         result = object->absoluteBoundingBoxRect();
     return result;
 }
 
 } // namespace blink