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

media/blink/webmediaplayer_impl.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_
 #define MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 530 matching lines @@
   base::OneShotTimer background_pause_timer_;
 
   // Monitors the watch time of the played content.
   std::unique_ptr<WatchTimeReporter> watch_time_reporter_;
   bool is_encrypted_;
 
   // Number of times we've reached BUFFERING_HAVE_NOTHING during playback.
   int underflow_count_;
   std::unique_ptr<base::ElapsedTimer> underflow_timer_;
 
+  // Whether the player is currently in autoplay muted state.
+  bool autoplay_muted_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_