Scanning when using a Chromebook is not a feature that is supported by the Chrome OS.
If you have an item that you wish to scan with your PIXMA MX922 and then save it on your Chromebook, you can can and save the item to a USB flash drive and then insert that flash drive into your Chromebook and move it to its hard drive.
To scan with your PIXMA MX922 and save to a USB flash drive, please view this page of the PIXMA MX922's On Line Manual: