The german language Software update of Photoshop Camera Raw (18.104.22.168) doesn't content the objective profile correction for the model Canon Powershot G15. I did already the latest update but it still does not recognize the camera.
The G15's raw format is supported by Adobe; however, beyond that, Adobe mostly only supplies lens-profiles for Canon and Nikon DSLRs, which the G15 is not. The lack of G15 lens profile is a choice Adobe has made, not an oversight or bug.
There are also no third-party profiles for the G15 available in the Adobe Lens Profile Downloader.
The only way to get a lens profile for your G15 is to make one, yourself, using the Adobe Lens Profile Creator software.
If it makes you feel any better, you're the second person to ask about this in as many days.