Marking test receiver as exported.

In order to follow the new dynamic receiver paradigm introduced in T, receivers will have to be specifically marked as exported or not exported when registering dynamically. Since this is in a test only, and the test says that it needs the broadcast to be in a different process, mark as exported.

Bug: 161145287
Change-Id: I112d56962e3a6c3043240f8dfab058dc5a728ba9
Test: atest HostsideRestrictBackgroundNetworkTests#testAppIdle_toast
2 files changed