[Media, Android] Fix lockscreen and other remote controls on KK-

The cause of the crash is the following:
- user starts playback on KK
- user tries to use remote control, e.g. lock screen
- the service gets an intent without the notification id and stops itself
- onServiceDestroy gets called with an invalid notification id so it doesn't clean up the manager
- next time the playback is started, the manager calls getIntent() with an invalid notification id
- the method returns null in this case

The fix: use distinct MediaButtonReceiver subclasses for the two supported notification ids to pass the right one with the intent MediaButtonReceiver sends to the service.


Review URL: https://codereview.chromium.org/1431023004

Cr-Commit-Position: refs/heads/master@{#358714}
3 files changed