This change moves the handling of any media button event into
`MediaSessionImpl.onMediaButtonEvent(intent)`. This includes
the double click handling from `MediaSessionLegacyStub`.
The advantage is that everything is in one place which allows
to offer `MediaSession.Callback.onMediaButtonEvent` with which
an app can override the default implementation and handle media
buttons in a custom way.
Media button events can originate from various places:
- Delivered to `MediaSessionService.onStartCommand(Intent)`
- A `PendingIntent` from the notification below API 33
- An `Intent` sent to the `MediaButtonReceiver` by the system dispatched
to the service
- Delivered to `MediaSessionCompat.Callback.onMediaButtonEvent(Intent)`
implemented by `MediaSessionLegacyStub` during the session is active
- Bluetooth (headset/remote control)
- Apps/system using `AudioManager.dispatchKeyEvent(KeyEvent)`
- Apps/system using `MediaControllerCompat.dispatchKeyEvent(keyEvent)`
Issue: androidx/media#12
Issue: androidx/media#159
Issue: androidx/media#216
Issue: androidx/media#249
#minor-release
PiperOrigin-RevId: 575231251
a79d44edc5