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 e9f9ba3a2b7fbdbf2ffd4e583e8cf446beea7d72..4de7e7601fe5a9b65415c2be6c4d66822413644f 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);
+
   // 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();
+}
+
 void HTMLMediaElement::requestReload(const WebURL& newUrl) {
   DCHECK(webMediaPlayer());
   DCHECK(!m_srcObject);