DO NOT MERGE Disallow Wallpaper service to launch activity from background.

Add a flag so that when a foreground client binds to a service,
disallow the bound service to launch activity from background.
Modify the WallpaperManagerService to take advantage of the new flag.

Test: atest BackgroundActivityLaunchTest WallpaperManagerServiceTests
Bug: 298094386
Change-Id: Id4e4cb6144597cf3638f2aaa34ea455a239fa1a7
8 files changed