I faced this humongous Chrome UI problem and stumbled upon this question on superuser, which uses the same Ubuntu version. I have followed the accepted answer there but apparently it does not have any effect. Is there a new workaround for this issue?
My display is not a HiDPI one, it is 1366x768, scaling factor is set at 0.875 in order to make text the same size as in Windows. Every other program follows this scaling, except Chrome.