A new commit recently added to the Chromium Gerrit suggests that Chrome OS users may see the Google Sans font used for titles following a future update. The main body of the code in question includes comments that indicate the font is being added at the system level in the Chrome OS directory at "/usr/share/fonts/google-sans." One of the associated 'bugs' meanwhile - specifically, Chromium:852034 - shows a template update which points toward the font's use specifically in titles. That would seem to imply that the font will become the de facto default for titles shown in the operating system. However, while speculative, that could also mean that the font will be assignable to other aspects of the user interface via Chrome OS appearance settings. If that's the case, users should be able to set any aspect they choose, such as all sans-serif type, to display in Google Sans.
With regard to the font itself, Google Sans is a natural progression of the search giant's cross-platform optimized typeface. That's because it is directly derived from Product Sans, used for the present Google logo, which is itself based on Android's system-level default Roboto font. This also isn't the first place the Material Design-inspired typeface has been spotted, as it was recently tested for inclusion in Android's Google search app. However, that other testing still hasn't resulted in a wide rollout and there's currently no way to know when the new font will begin making appearances in Chrome OS. It's unlikely that any major bugs will prevent the font from being added but the process isn't always seamless. The change will undoubtedly show up in the Canary and Developer Channels of the OS first in order to ensure there aren't any problems. So it could be several months before everyday users see the effects of the new code on their Chromebook or other Chrome OS device.
In the meantime, the above-mentioned bug report shows that the incoming change is part of a larger reworking of the overall U.I. for Chrome OS. Setting aside Google Sans, work is underway to add GM2 UI components such as buttons, dropdown, textfield, icons, toggles, checkbox. That's in addition to a new 'Shelf color update' and other color schema changes seemingly intended to push things further in the direction of a redesigned Material Design standard.