LoadUSBDevices renamed and moved into separate file. DriversListAdapter moved into separate file. LoadUSBDevices refactored to return list of usb drivers to onPostExecute that makes a call to update the list on UI thread.
Check for valid menu resource id
Switched from ActionBar to Toolbar. Refactored part of code that starts service for USB_DEVICE_ATTACHED intent
Moved inner classes into separate files
Replaced conditional cluster-fk with ternary
onPostExecute is already running on UI thread, no need for extra code
getApplicationIcon will never return null but a default icon instead