WifiScanner: Changes to support hidden Network Ids

Add the required plumbing to support scanning for hidden networks via
wpa_supplicant.
Added a test case to verify that the network ID list is being sent
as expected.

BUG: 27503786
Change-Id: I2d1ef74494080e01248ae8aad5081c7608fc0e81
TEST: Compiles & unit-test passes
7 files changed
tree: fd0ea751d3108b75d9c29808ca9aa5c3441321b6
  1. service/
  2. tests/