Unregister hotspot receiver in TetherService.

- when the service exits, also unregister the hotspot receiver.
- move TetherService and HotspotOffReceiver to wifi.tether package.

Change-Id: I0044a52bf80a5530a58b5186ab056de55e83532b
Fixes: 69844871
Test: make RunSettingsRoboTests

src/com/android/settings/wifi/tether/HotspotOffReceiver.java

@@ -0,0 +1,55 @@
+
+package com.android.settings.wifi.tether;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.net.ConnectivityManager;
+import android.net.wifi.WifiManager;
+import android.util.Log;
+
+/**
+ * This receiver catches when quick settings turns off the hotspot, so we can
+ * cancel the alarm in that case.  All other cancels are handled in tethersettings.
+ */
+public class HotspotOffReceiver extends BroadcastReceiver {
+
+    private static final String TAG = "HotspotOffReceiver";
+    private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
+
+    private Context mContext;
+    private boolean mRegistered;
+
+    public HotspotOffReceiver(Context context) {
+        mContext = context;
+    }
+
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        if (WifiManager.WIFI_AP_STATE_CHANGED_ACTION.equals(intent.getAction())) {
+            WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
+            if (wifiManager.getWifiApState() == WifiManager.WIFI_AP_STATE_DISABLED) {
+                if (DEBUG) Log.d(TAG, "TetherService.cancelRecheckAlarmIfNecessary called");
+                // The hotspot has been turned off, we don't need to recheck tethering.
+                TetherService.cancelRecheckAlarmIfNecessary(
+                        context, ConnectivityManager.TETHERING_WIFI);
+            }
+        }
+    }
+
+    public void register() {
+        if (!mRegistered) {
+            mContext.registerReceiver(this,
+                new IntentFilter(WifiManager.WIFI_AP_STATE_CHANGED_ACTION));
+            mRegistered = true;
+        }
+    }
+
+    public void unregister() {
+        if (mRegistered) {
+            mContext.unregisterReceiver(this);
+            mRegistered = false;
+        }
+    }
+}