Expose media controls to accessibility

content/public/browser/media_session.h

 // Copyright 2016 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 CONTENT_PUBLIC_BROWSER_MEDIA_SESSION_H_
 #define CONTENT_PUBLIC_BROWSER_MEDIA_SESSION_H_
 
 #include "base/macros.h"
 #include "content/common/content_export.h"
 
@@ skipping 37 matching lines @@
   // |type| represents the origin of the request.
   virtual void Suspend(SuspendType suspend_type) = 0;
 
   // Resume the media session.
   // |type| represents the origin of the request.
   virtual void Stop(SuspendType suspend_type) = 0;
 
   // Tell the media session a user action has performed.
   virtual void DidReceiveAction(blink::mojom::MediaSessionAction action) = 0;
 
+  // Let the media session start ducking such that the volume multiplier is
+  // reduced.
+  virtual void StartDucking() = 0;
+
+  // Let the media session stop ducking such that the volume multiplier is
+  // recovered.
+  virtual void StopDucking() = 0;
+
  protected:
   MediaSession() = default;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_MEDIA_SESSION_H_