Read the article - they specifically talk about drawing your own pointer. You don't need to control the pointer, you just need to make it appear to be somewhere else.
Remember all the shitty spam adverts themed to look like Windows XP dialog boxes? I can't wait to see what the bottom-feeders can come up with given this sort of feature.
At least it sounds like Chromium uses a modal yes/no question bar.
The mouse sends high DPI information to the OS, and the OS sends the applications the mouse info they request.
For drawing the pointer in the GUI, lots of DPIs correspond to moving just one pixel.
However, that's just too low resolution for gaming, where the full DPI information is preferable. Also, for gaming, mouse acceleration should be disabled.
The solution in other games is to read the original high DPI info, instead of the mouse screen coordinates.
Of course you are right about spam, but there's a technical reason for this implementation.
Remember all the shitty spam adverts themed to look like Windows XP dialog boxes? I can't wait to see what the bottom-feeders can come up with given this sort of feature.
At least it sounds like Chromium uses a modal yes/no question bar.