Pretend the video has no audio track if it is playing as part of autoplay muted.

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 2274 matching lines @@
       !paused() && m_muted && isLockedPendingUserGesture();
   bool wasPendingAutoplayMuted = m_autoplayVisibilityObserver && paused() &&
                                  m_muted && isLockedPendingUserGesture();
 
   if (UserGestureIndicator::processingUserGesture())
     unlockUserGesture();
 
   m_muted = muted;
   m_autoplayHelper->mutedChanged();
 
-  updateVolume();
-
-  scheduleEvent(EventTypeNames::volumechange);
-
   // If an element autoplayed while muted, it needs to be unlocked to unmute,
   // otherwise, it will be paused.
   if (wasAutoplayingMuted) {
     if (isGestureNeededForPlayback()) {
       pause();
       m_autoplayUmaHelper->recordAutoplayUnmuteStatus(
           AutoplayUnmuteActionStatus::Failure);
     } else {
       m_autoplayUmaHelper->recordAutoplayUnmuteStatus(
           AutoplayUnmuteActionStatus::Success);
     }
   }
 
+  updateVolume();
+
+  scheduleEvent(EventTypeNames::volumechange);

[foolip, 2016/10/10 11:33:07]

This will change the order of events from volumechange, pause to pause,
volumechange. I guess there's no test coverage for this, can you preserve the
behavior and file a follow-up to test
https://html.spec.whatwg.org/multipage/embedded-content.html#dom-media-muted?

[mlamouri (slow - plz ping), 2016/10/31 15:27:41]

Just to clarify, do you want me to revert the change or keep this change and
update the spec? My understanding is that you want to revert the change. In
which case, I will have to replace this with some ugly work arounds. Is this
okay?

[foolip, 2016/11/01 16:12:21]

Maintaining the event order seems best, yeah.

+
   // If an element was a candidate for autoplay muted but not visible, it will
   // have a visibility observer ready to start its playback.
   if (wasPendingAutoplayMuted) {
     m_autoplayVisibilityObserver->stop();
     m_autoplayVisibilityObserver = nullptr;
   }
 }
 
 void HTMLMediaElement::updateVolume() {
   if (webMediaPlayer())
@@ skipping 689 matching lines @@
     mediaControls()->stoppedCasting();
   if (remotePlaybackClient())
     remotePlaybackClient()->stateChanged(WebRemotePlaybackState::Disconnected);
 }
 
 void HTMLMediaElement::cancelledRemotePlaybackRequest() {
   if (remotePlaybackClient())
     remotePlaybackClient()->promptCancelled();
 }
 
+bool HTMLMediaElement::isAutoplayingMuted() {
+  if (!isHTMLVideoElement() ||
+      !RuntimeEnabledFeatures::autoplayMutedVideosEnabled())
+    return false;
+
+  return muted() && isLockedPendingUserGesture();

[foolip, 2016/10/10 11:33:07]

This will return true even if not actually playing, intentional?

[mlamouri (slow - plz ping), 2016/10/31 15:27:41]

That was on purpose but I've added a check to make it less confusing.

+}
+
 void HTMLMediaElement::requestReload(const WebURL& newUrl) {
   DCHECK(webMediaPlayer());
   DCHECK(!m_srcObject);
   DCHECK(newUrl.isValid());
   DCHECK(isSafeToLoadURL(newUrl, Complain));
   resetMediaPlayerAndMediaSource();
   startPlayerLoad(newUrl);
 }
 
 // MediaPlayerPresentation methods
@@ skipping 959 matching lines @@
 
 IntRect HTMLMediaElement::AutoplayHelperClientImpl::absoluteBoundingBoxRect()
     const {
   IntRect result;
   if (LayoutObject* object = m_element->layoutObject())
     result = object->absoluteBoundingBoxRect();
   return result;
 }
 
 }  // namespace blink