Simplify: drop unused stop() from NetworkConnectionMonitor

The monitor is registered once for the whole process lifetime and never torn
down, so stop() had no callers. Removing it also lets the handlerThread and
networkCallback fields go — they were only read by stop(). connectivityManager
stays since hasActiveConnection() uses it.

Author: nbradbury

WordPress/src/main/java/org/wordpress/android/networking/NetworkConnectionMonitor.kt

@@ -28,8 +28,6 @@ class NetworkConnectionMonitor @Inject constructor() {
     private var isFirstCallback = true
 
     private var connectivityManager: ConnectivityManager? = null
-    private var handlerThread: HandlerThread? = null
-    private var networkCallback: ConnectivityManager.NetworkCallback? = null
 
     class ConnectionChangeEvent(val isConnected: Boolean)
 
@@ -41,31 +39,16 @@ class NetworkConnectionMonitor @Inject constructor() {
         connectivityManager = manager
 
         val thread = HandlerThread("NetworkConnectionMonitor").apply { start() }
-        handlerThread = thread
-
         val callback = object : ConnectivityManager.NetworkCallback() {
             override fun onAvailable(network: Network) = onConnectivityChanged(true)
             // onLost fires for the network that was lost, but during a handover (e.g. Wi-Fi -> cellular) the
             // new default has already arrived via onAvailable, so re-query rather than assuming we're offline.
             override fun onLost(network: Network) = onConnectivityChanged(hasActiveConnection())
         }
-        networkCallback = callback
-
         manager.registerDefaultNetworkCallback(callback, Handler(thread.looper))
         started = true
     }
 
-    @Synchronized
-    fun stop() {
-        if (!started) return
-        networkCallback?.let { connectivityManager?.unregisterNetworkCallback(it) }
-        handlerThread?.quitSafely()
-        networkCallback = null
-        handlerThread = null
-        connectivityManager = null
-        started = false
-    }
-
     /**
      * Called on the monitor's background thread. Posts a [ConnectionChangeEvent] on the first callback and
      * whenever the connected state actually changes, so subscribers aren't spammed when a network's