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

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 7d88fc290a96ebbcab97133b577b56a7a49b07f2..79681ec8c51f0de70f99218df24faf649d969344 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
@@ -2292,10 +2292,6 @@ void HTMLMediaElement::setMuted(bool muted) {
   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) {
@@ -2309,6 +2305,10 @@ void HTMLMediaElement::setMuted(bool muted) {
     }
   }
 
+  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) {
@@ -3018,6 +3018,14 @@ void HTMLMediaElement::cancelledRemotePlaybackRequest() {
     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);