ScanRequestProxy: Add a separate bg scan throttle mechanism
The current scan throttling mechanism is too lenient for background
apps. So, split the throttling logic into two:
a) For foreground apps, continue to throttle to a max of 1 scan per app
every 30 seconds.
b) For background apps, throttle to a max of 1 scan from any background
app every 30 minutes.
Bug: 68987915
Test: Unit tests
Change-Id: I57915226e3be332ad6934e81ad69c218fe17ad30
Merged-In: I7c392429f8abaa00ea29b0a4479d010415d7b0ef
3 files changed