Simple mod to back up all your photos in Original quality to Google Photos without it being only in High Quality.
1. Download Root Explorer
2.Download the Nexus.xml file
3. In Root Explorer go to system/etc/sysconfig
4. Paste the .XML file there
5. Change to file permissions to 0444 (read only)
6. Clear Data/Cache from Google Photos
8.Enjoy unlimited original photos backup
For those who this method doesn't work, there's another method I've found.
For this method you'll need BuildPropapp.
Download the app from the file I've provided or from playstore.
Open the app , At top right corner you'll find a pencil icon. click on it, You'll see a list of codes.
Now you can either manually find the following values or use the find option in the menu from top right corner.