Please note before upgrading to macOS Sierra 10.12.5:
We’ve received reports wherein Google Docs open in the wrong/non-default browser when opening the “.gddocs” or “.gdsheet” files in the Insync folder.
From our testing and based on this forums post – only users on the latest macOS 10.12.5 are affected by this. This post on the Apple forums suggests that the update affects other services too: https://discussions.apple.com/thread/7959365?start=0&tstart=0
We’re checking if there’s an Insync workaround for this but Apple should be looking into this as well.
We’ll post updates here.