Google Chrome’s popup blocker actually allows all popups to load, it just hides them from view. The popup doesn’t even know, so to speak, that it has been blocked. Content is still downloaded and rendered, off screen. If you choose to allow that popup instance, the window is drawn and you see the content that has already rendered: no refreshing or reloading.
I actually prefer this behavior. When Internet Explorer blocks a popup and you choose to allow it, the entire parent page refreshes – resubmitting forms and other annoyances along the way – and allows any popups that might be triggered to load. That is the important distinction; the original popup is destroyed without ever being seen. The server, upon this next page load, could send a different popup (or none at all if your shopping cart purchase resubmission just caused an error), or the popup could be random as in an advertisement or otherwise. Not exactly ideal, and I don’t know why Microsoft used that method (I can only assume it was lazy coding or the better version was patented).
Google clearly chose to support the user experience. Or did they? Consider that Google’s main source of revenue by far is advertising. Without internet ads, nothing else Google has ever done would have happened. It is their business. Also consider that these advertisements generate revenue in some cases by how many times they are viewed (and certainly it can’t hurt view statistics). Seems like allowing those popups to load, even if users ignore them behind the icon, can be pretty good business.