Google has declared war on programs that compromise the integrity of users browsing experience across the globe. An ad injector is a program that performs its injection activities between legitimate websites, and the users web browser. Google determined that thirty-four percent of Google Chrome extensions found to be injecting advertisements could be classified as outright malware Google also stated that they have already found approximately 192 Chrome extensions that attempted to deceive users. Google has since disabled these benign or malicious extensions, and we can only speculate that there are many more extensions that will perish.”]
Source: http://securityaffairs.co/wordpress/35642/malware/google-war-versus-ad-injectors.html