Use fdevent_run_on_main_thread to initialize mDNS in a thread and
register an fdevent from the main thread upon success.
This reduces the startup time of `adb server` by ~3 seconds when mDNS
can't be successfully started. With an already running adb server,
`time adb server nodaemon` goes from:
adb server nodaemon 0.00s user 0.16s system 4% cpu 3.817 total
to:
adb server nodaemon 0.00s user 0.01s system 1% cpu 0.665 total
Bug: http://b/37869663
Test: `adb server nodaemon` with an existing adb server
Change-Id: Ia5a1a2a138610f3bf6792400050ca68f95ae3734
Test: Verified ADB over mDNS on a Windows machine
Bug: 30482671
(cherry picked from 9fdd77101f49d03ff29342e12e23edf241f68522)
Change-Id: If955ca304db71a5b08c5a9654f1e27ab74af9af8
We have to disable IPv6 to get this going, but nobody was yet using
IPv6, so that should be fine for now.
Test: Verified mDNS discovery on a MacBook
Bug: 31042497
(cherry picked from 9ae65de087171072f3890a81b074ae27db319508)
Change-Id: I628f0a1e9c4784db42fa56f5faf2904b6e1cf548
Test: Was able to discover a raspberry pi.
Bug: 28074466
(cherry picked from e292cd16760321fccc99c8c261cb92fa4b6462ab)
Change-Id: Id9571576457a4a0a078e48a274a4e8eac78bfe2b