When we sent the very first Chrome out to reviewers, one reviewer sent back a draft of a review that said Chrome seemed like a nice browser but it had the strange additional feature of popping up ads inside the pages as you browsed.
The reviewer was so accustomed to their existing browser simply blocking pop-ups that it didn't occur to them that the pop-ups were caused by the pages they were visiting, and instead thought it was some Chrome monetization strategy!
Because of this, the feature was scrapped at the last second. There is still some "constrained window" code left over in Chrome that is still used for e.g. HTTP auth prompts. Because the ports came later, I seem to recall we didn't bother with implementing all the draggy window management stuff on Linux and instead centered a dialog over the page content without the window manager controls.
You can search on http://cs.chromium.org for [constrained_window] to see some of the remaining code.