IMHO, I have no real objection to small advertising files being part of each page I view - its pretty much a necessary evil - as long as it doesnt consume huge amounts of bandwidth. But I do object to large video stuff, flash etc, so surely surely "Third Party Injectors" have NO place on the web.
For the system of ad supporting content to work then the page owner gets to decide who he is selling ad space to and receive something for each page impression viwed, not some scammer coding hidden function into extensions which pretty much become malware.
As a company that has grown on the back of advertising, Google should understand this and stop ALL the injectors - unless they can be shown to be financially contributing to the upkeep on the sites they steal advertising space on.
But then we know that ad men are the most venal of groups.