Implement one-shot audio focus inside MediaSession

media/base/media_content_type.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 MEDIA_BASE_MEDIA_CONTENT_TYPE_H_
 #define MEDIA_BASE_MEDIA_CONTENT_TYPE_H_
 
 #include "base/time/time.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
 // The content type of a media player, which will be used by MediaSession to
 // control its players.
 enum class MediaContentType {
   // Type indicating that a player is persistent, which needs to take audio
   // focus to play.
   Persistent,
   // Type indicating that a player only plays a transient sound.
   Transient,
   // Type indicating that a player is a Pepper instance. MediaSession may duck
   // the player instead of pausing it.
   Pepper,
-  // Type indicating that a player cannot be controlled. MediaSession wil ignore
-  // this player.
-  Uncontrollable
+  // Type indicating that a player cannot be controlled. MediaSession will take
+  // audio focus when the player joins but will not let it respond to audio
+  // focus changes.
+  OneShot,
+  // The maximum number of media content types.
+  Max = OneShot,
 };
 
 // Utility function for deciding the MediaContentType of a player based on its
 // duration.
 MEDIA_EXPORT MediaContentType
 DurationToMediaContentType(base::TimeDelta duration);
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_MEDIA_CONTENT_TYPE_H_