tree a7c8bd4bf0a571b85384700862a55557d4bd578e
parent 9f76ba17bc2d2d21a3f53debf14a74886c43daf5
author calvinpan <calvinpan@google.com> 1541034570 +0800
committer calvinpan <calvinpan@google.com> 1541599952 +0800

Add a url for getting the current APN list

There has three steps:
1. Query the APN based on carrier ID and fall back to query { MCC, MNC, MVNO }.
2. If can't find the current APN, then query the parent APN. Query based on
   MNO carrier id and { MCC, MNC }.
3. else return empty cursor

Bug: 115709816
Test: run TelephonyProviderTest
Change-Id: I573e5279ee37e9325880fb1527a698da7e24fb9f