Fix DeviceConfig flag read in Binder thread

A DeviceConfig flag was being read in the Binder thread, which would
cause a SecurityException instead of the expected exception.  Wrapping
the flag read in a BinderFlagReader call should return the correct
exception instead.

Test: atest CtsAdServicesDebuggableDeviceTestCases
Fixes: 298317200
Change-Id: I0d33e594fa03bbc2ceb5bc20598d04f5ff09e2c0
2 files changed