Add uid to PendingStartActivityUids when activity resumed.

Previously we add uid to PendingStartActivityUids at activity start.
Now we also add uid to PendingStartActivityUids at activity resumed
because we can not wait for updateOomAdj() to be run by a runnable that
WindowManager send to DisplayThread at activity resumed.

At ActivityManagerService.getProcessStatesAndOomScoresForPIDs(), if the
ProcessRecord is in PendingStartActivityUids, we hard code the
ProcessRecord to be PROCESS_STATE_TOP and FOREGROUND_APP_ADJ, ahead of
result of updateOomAdj() the comes later.

Bug: 155143386, 157180494
Test: Reproduce steps of 155143386, swipe between GCA and
Snapchat, camera access is allowed after swipe.

Change-Id: Ia11b0e3400e4df851b250beb01dcfda43580668b