Add launchDeviceDiscovery when devices just plugged into the current device or the
current device just conneted to a TV.

ag/5288659

Also modified DeviceDiscoveryAction to apply to both TV and Source devices.

Test: local tested.
Bug: 117291910
Change-Id: Iac5d191d1c78560807a408fc30cbf3f160260138
4 files changed