I am using a Mac with retina display running windows 8.1 and I used a combination of two of the answers here which worked perfectly for me if anyone is interested.
When I tried using just the chrome://flags HiDPI option it completely screwed up chrome so much so that I had to clear my user data and start again.
I tried Jazzbo's answer (setting "Disable display scaling on high DPI settings" in the compatability tab and that fixed the tabs bunching up issue but everything was very very small. then I tried to re-enable the HiDPI flag as davefromcamp suggested and it made it perfect! :D