Added defensive code to prevent system crash

Bug: 26940611
Change-Id: I8226d1acb42ccc7d2cd910e30b47c7c63c9f490b

services/core/jni/com_android_server_location_FlpHardwareProvider.cpp

@@ -661,6 +661,16 @@ static void GeofenceMonitorStatusCallback(
     TranslateToObject(lastLocation, locationObject);
   }
 
+  // sCallbacksObject is created when FlpHardwareProvider on Java side is
+  // initialized. Sometimes the hardware may call this function before the Java
+  // side is ready. In order to prevent the system crash, check whether
+  // sCallbacksObj has been created. If not, simply ignore this event from
+  // hardware.
+  if (sCallbacksObj == NULL) {
+    ALOGE("FlpHardwareProvider hasn't been initialized.");
+    return;
+  }
+
   sCallbackEnv->CallVoidMethod(
       sCallbacksObj,
       sOnGeofenceMonitorStatus,