Fix issue #7097984b java.lang.SecurityException: Permission Denial:

broadcast asks to run as user -1 but is calling from user 0; this requires

Also improve part of issue #7087789: Local denial of service via
low-permissioned apps

No longer allow closeSystemDialogs() from background processes.

Change-Id: I752d5a1d51be0b69fde6999d6659835e5bde3efe