That's Maximized. Not fullscreen. Fullscreen is a bit different. What does it do on Windows when you use Chrome's Fullscreen option? Fake edit: Well now. Windows Chrome doesn't have a Fullscreen option? What gives? I guess Fullscreen must be an OS X thing. Which is interesting because Fullscreen makes the window take up the WHOLE screen including removing the menubar and Dock. Does Linux have Fullscreen?
Windows with Maximizing:
OS X with Fullscreen:
You get more pixels in OS X. And would get even more if they removed the top buffer. Of course, this is Chrome Canary so hopefully someone realizes this before release. But I assume they kept the buffer there to prevent activating the menubar. Which is why it should have a delay. But I suspect the menubar slide delay is controlled by OS X and not the app developer.
Edit: Even Firefox has Fullscreen in Windows. Chrome MUST have it. But I can't find an actual menubar in Chrome on Windows.