Just in time for Black Friday and the upcoming holiday shopping season, Google confirmed on the Google Maps Twitter account today that indoor floor plans are now available to all Google Maps users on the desktop. Unfortunately, unlike Android users who have access to multi-floor views, Google Maps on the desktop currently only shows the main level of buildings for indoor floor plans:
Currently, desktop Google Maps users are only able to view the main level of buildings available in indoor maps. For Maps users on Android devices, you can see additional levels using the level switcher function on the right side of the map.
Google has a full list of locations with indoor maps here.