It's bad enough when apps add unwanted toolbars and buttons in your browser, but it's especially irksome when they inject ads. It's no fun to have a technical support scam interrupt your web reading, after all. Google clearly hates this rogue software as much as you do, though, as it just outlined what it's doing to fight ad injectors. In Chrome, the company's tougher extension rules and malware blockers theoretically prevent code from inserting ads without your say-so. Google is also refining its techniques for catching bad extensions, and its AdWords policies prevent advertisers from offering shady downloads.