SoftApCallback using executor vs handler

Updating classes to support making SoftApCallback methods available to @SystemAPI including
the API for registration of a SoftApCallback which includes a change to
now use executor vs handler.

Bug: 143564153
Test: make RunSettingsRoboTests ROBOTEST_FILTER=WifiTetherPreferenceControllerTest
Also tested manually on a Hawk.

Change-Id: I952ad10dd88b7d97b3cd86b269b8f67b00b1fa15
diff --git a/src/com/android/settings/wifi/tether/WifiTetherSoftApManager.java b/src/com/android/settings/wifi/tether/WifiTetherSoftApManager.java
index 1a805bd..3de5869 100644
--- a/src/com/android/settings/wifi/tether/WifiTetherSoftApManager.java
+++ b/src/com/android/settings/wifi/tether/WifiTetherSoftApManager.java
@@ -3,6 +3,7 @@
 import android.net.wifi.WifiClient;
 import android.net.wifi.WifiManager;
 import android.os.Handler;
+import android.os.HandlerExecutor;
 
 import java.util.List;
 
@@ -35,7 +36,7 @@
     }
 
     public void registerSoftApCallback() {
-        mWifiManager.registerSoftApCallback(mSoftApCallback, mHandler);
+        mWifiManager.registerSoftApCallback(mSoftApCallback, new HandlerExecutor(mHandler));
     }
 
     public void unRegisterSoftApCallback() {