Pause autoplay muted video when unmuting if there's no user gesture

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

Index: third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
index 441ee5b55a8b6e020d888087c1062bc553bea0e0..50c260c45b7fe8fa549208ac4a36478718a08463 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
@@ -431,6 +431,7 @@ HTMLMediaElement::HTMLMediaElement(const QualifiedName& tagName, Document& docum
     , m_remoteRoutesAvailable(false)
     , m_playingRemotely(false)
     , m_inOverlayFullscreenVideo(false)
+    , m_isAutoplayingMuted(false)
     , m_audioTracks(AudioTrackList::create(*this))
     , m_videoTracks(VideoTrackList::create(*this))
     , m_textTracks(nullptr)
@@ -2260,6 +2261,9 @@ void HTMLMediaElement::setMuted(bool muted)
 {
     DVLOG(MEDIA_LOG_LEVEL) << "setMuted(" << (void*)this << ", " << boolString(muted) << ")";
 
+    if (UserGestureIndicator::processingUserGesture())
+        unlockUserGesture();
+
     if (m_muted == muted)
         return;
 
@@ -2274,6 +2278,13 @@ void HTMLMediaElement::setMuted(bool muted)
         Platform::current()->recordAction(UserMetricsAction("Media_Playback_Mute_Off"));
 
     scheduleEvent(EventTypeNames::volumechange);
+
+    if (!muted && m_isAutoplayingMuted) {

[foolip, 2016/06/09 11:41:43]

As per https://github.com/whatwg/html/issues/976 I don't think should depend on
whether the reason that we're playing, but rather that when setting muted to
false and it was previously true and there is no user gesture, the internal
pause steps should be run.

That's easy to explain and avoids that extra state bit.

+        // Pause the element autoplayed muted when unmuting if there was no user gesture.
+        if (isLockedPendingUserGesture())
+            pause();
+        m_isAutoplayingMuted = false;
+    }
 }
 
 void HTMLMediaElement::updateVolume()
@@ -3671,13 +3682,17 @@ void HTMLMediaElement::unlockUserGesture()
     m_lockedPendingUserGesture = false;
 }
 
-bool HTMLMediaElement::isGestureNeededForPlayback() const
+bool HTMLMediaElement::isGestureNeededForPlayback()
 {
+    m_isAutoplayingMuted = false;
+
     if (!m_lockedPendingUserGesture)
         return false;
 
-    if (muted() && RuntimeEnabledFeatures::autoplayMutedVideosEnabled())
+    if (muted() && RuntimeEnabledFeatures::autoplayMutedVideosEnabled()) {
+        m_isAutoplayingMuted = true;
         return false;
+    }
 
     if (m_autoplayHelper->isGestureRequirementOverridden())
         return false;