At the beginning of each song, the Music app re-registers its
media button event and requests audio focus, which causes
the reevaluation of each corresponding stack of clients. Each
reevaluation is accompanied by the incrementation of the
RemoteControlClient generation ID, which causes RemoteController
to issue a notification that the client has changed. The lockscreen
correctly interprets this as a reason to dump the current
RemoteControlClient data (including the artwork) because it will
receive the new data if new one is available. This is what causes
the "flashing" of the wallpaper on the lockscreen: for an instant,
no client data is available.
The fix consists in not causing the client generation ID to be
incremented when registrations don't cause any change in the
RemoteControlClient stack. Even though Music re-registers everything,
nothing has changed: it still is the current media button receiver,
and it still has the same RemoteControlClient.
Bug 11307382
Change-Id: I4d2404b571e88aeedb0eca6bd19d39f7ec4fc8b1
0b60534917