"Keychain" is an app that runs on macOS. It interfaces only with macOS and iOS apps that come from Apple, such as Safari — it does not connect to or act with software like Chrome that doesn't come from Apple.
Google Password Manager does password management with Chrome, including Chrome running on macOS.
On this stack, the tag "Keychain" refers to Keychain the Apple app, not to password managers generally. You should delete this tag, and substitute the tag "Password."