Contour Timesync OTG

The app sets the clock of your Contour Roam Actioncam after charging.
!!! Requires an 'USB OTG'-capable cellphone and an 'USB OTG' cable !!!
--- About ---
I've bought a Contour Roam helmet camera to easily and securely take fotos on the motorcycle while driving.
The camera's built-in clock stores each foto with the current timestamp (given it has accurately synchronized time) which I then can associate with the locations I visited using logs from my GPS or memorized or estimated times.
For one-day-trips that worked just fine, but after a several-day-trip I realized that the internal clock stops while charging the camera, resulting in discrepancies of several hours, growing each day.
Because I did not want to take my laptop with me on the bike, I wrote this synchronization app that can easily correct the clock on the camera after charging it in the evening, and since I assumed that other Roam-owners have the same problem...
If a different Contour camera also has this problem, do not hesitate to contact me and I will see what I can do.
I could only test it with a Contour Roam on a Samsung Galaxy Nexus, and I would be grateful for feedback about other devices.
This app is my first contribution to Android and actually I wrote it just for myself, so please be gentle with the rating. ;)
--- Usage ---
Connect the camera via the USB OTG-cable to the phone, so that you can access the file system on the camera via the phone.
Open the app, there you should see the difference between the current time and the time the camera's clock has been set to.
Press the 'sync' button, then the clock will be prepared correctly (plus a configured amount of seconds as an offset), but it is not yet set. You need to first disconnect the camera from your phone properly and turn it on (just for a few seconds), the best time to do the latter is when the difference between the current and the time in the camera reaches zero.
If your phone does not support USB OTG innately (what, unfortunately, only the fewest Android phones do), then you need to unlock it first and extend it with an appropriately expanded custom ROM (e.g. AOKP), or, easier, root it and extend it with a small utility such as Stick Mount by Chainfire.
If everything goes well, and you can access the filesystem of e.g. an USB-stick with your phone and a filemanager-app, then you're ready, and it will also work with your Contour Roam.
The app is not supposed to cause any problems, but if, by any unforeseen reasons, the configuration file of the camera should be damaged in any way, just delete the file from the camera and it will automatically create a fresh one the next time you power it up.
If data loss or file errors on the camera occur, then this is most probably not the fault of my app but the camera has probably been disconnected from the phone or a computer and to fix it the camera needs to be formatted or at least has to have a complete file system check!
Never pull a data carrier from your phone or computer without having it unmounted properly by software beforehand!
The brutest (but perfectly working) way I know is to turn off the phone/computer, and then remove the camera/USB-stick.