1
If you double click the top bar on the Chrome browser, does the Chrome window then maximize to full screen?
2
If not, on the Taskbar, hover your mouse over the Chrome icon on the Taskbar, when the thumbnail appears, right click it and select Maximize, does the Chrome window then maximize to full screen?
3
If that does not resolve the problem, open the Settings App, then go to Apps.
Scroll down to find Chrome, select it, choose Modify and repair the Chrome installation.
4
If that does not resolve the problem, completely uninstall Chrome, then restart (not shut down) your PC and download the latest version of Chrome form the Google website.