When you sign in Google Chrome with you credentials it will automatically sign you in all Google services (Drive, GMail, Keep, Calendar, Search, etc...). This can be useful but can also expose your personal data since there is no default way to protect Chrome with a password.
Google says in the help page the only way to do this is by using the Incognito Mode. That's not true. There is a way to keep your Chrome Browser signed in and at the same time be signed out of other Google services. This takes less than 30 seconds and does not require the installation of any app or plugin.