I've found this info on Chromebook help website:
If your printer can't be saved automatically, you can use the advanced setup process.
If your printer doesn't appear in the manufacturer or model drop-down menus, Chromebook may not support your printer. You can try to use a "Generic" Postscript Printer Description (PPD) from the drop-down menus or you can specify your own PPD.
Chromebooks use PPD files to support printers. PPD files are different from printer drivers and tell your Chromebook how to support a specific printer model.
To use your PIXMA MG2520 with your Chromebook, it must first be set up for use with a Windows or Mac computer using a USB cable. To print from your Chromebook, after it is setup for use with a Windows or Mac computer, it must be set up as a Classic Printer on that computer. To do this, please follow the steps for connecting a Classic Printer from Google's web site:
I've found the driver, but it's not in ppd or gzip format. I'm admittedly weak in this area of technology. Would love a step by step. I've plugged the printed into my computer and the set up pop up is asking me to configure the printer.