"file a bug" - go to
crbug.com and click on "New issue".
"attaching the output of devtools" - when experiencing the issue on Google Maps, press F12, go to the Console panel and copy everything from there to the issue you create.
"the state of chrome://gpu/" - type chrome://gpu in the address bar of the browser and press Enter. Wait about half a minute for the browser to gather some data and copy everything from there to the issue you create.
(If you can attach to the issue you create a separate text file for each output instead of just pasting the entire thing into the issue, that would be helpful)