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

media/blink/webmediaplayer_impl.h

Index: media/blink/webmediaplayer_impl.h
diff --git a/media/blink/webmediaplayer_impl.h b/media/blink/webmediaplayer_impl.h
index 729d41ec4334c2d0b0c9ab65c59daad4e9fb77ef..d9557a3a9e9b73a0397b2e76da635e968285e537 100644
--- a/media/blink/webmediaplayer_impl.h
+++ b/media/blink/webmediaplayer_impl.h
@@ -566,6 +566,9 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
   // Monitors the player events.
   base::WeakPtr<MediaObserver> observer_;
 
+  // Whether the player is currently in autoplay muted state.
+  bool autoplay_muted_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerImpl);
 };