Return generic Binder on onBind

By returning a generic Binder on onBind in
ImsServiceBase, we can detect when the process
crashes and restart the service, if necessary.

Test: Telephony Unit Tests
Change-Id: I2fbe2708c3df37704f0c526210267a35c75ee1eb

telephony/java/android/telephony/ims/ImsServiceBase.java

@@ -19,6 +19,7 @@ package android.telephony.ims;
 import android.annotation.SystemApi;
 import android.app.Service;
 import android.content.Intent;
+import android.os.Binder;
 import android.os.IBinder;
 
 /**
@@ -30,8 +31,15 @@ import android.os.IBinder;
 @SystemApi
 public class ImsServiceBase extends Service {
 
+    /**
+     * Binder connection that does nothing but keep the connection between this Service and the
+     * framework active. If this service crashes, the framework will be notified.
+     */
+    private IBinder mConnection = new Binder();
+
     @Override
     public IBinder onBind(Intent intent) {
-        return null;
+        return mConnection;
     }
+
 }