Google seems to have updated the terms and conditions of their Chrome Web Store.
Developers can now incorporate ads into their extensions and apps. There are some conditions that Google wants them to follow:
Ads Context and Attribution:
Ads must be presented in context with your app or clearly state which app they are bundled with. Ads must also be easily removable by either adjusting the settings or uninstalling the app(s) altogether. Ads may not simulate or impersonate system notifications or warnings.
Forcing the user to click on ads or submit personal information for advertising purposes in order to fully use an app provides a poor user experience and is prohibited.
Interfering with Third-party Ads and Websites:
Ads associated with your app may not interfere with any ads on a third-party website or application. You may show ads alongside a third-party website only if all of the following criteria are met:
This behavior is clearly disclosed to the user.
There is clear attribution of the ads’ source wherever those ads appear.
The ads do not interfere with any native ads or functionality of the website.