Address leftover comments on aosp/2596565 & aosp/2593907 includes - Rename onAllSocketsDestroyed to onSocketDestroyed - Move SocketKey into SocketInfo - Remove getInterfaceIndex dependency. Bug: 278018903 Test: atest FrameworksNetTests android.net.cts.NsdManagerTest Change-Id: Ia37804f18d8e9abbd12d4b929b71dce5fa19d4f0