• Google enforces a strict, single-purpose policy for all Chrome extensions. This single-use policy demands that all Chrome extensions clearly state their purpose and stick solely to this purpose.
• The Chrome Developer portal explains this policy further as: "limited to a narrow focus area or subject matter (for example, news headlines", "weather", "comparison shopping"). If the extension has a narrow focus area or subject matter, then it can offer various functions related to that focus area or subject matter. For example, a news headlines extension could have a browser action button that allows users to see news stories and replace the new tab page with news-only content, so long as all of those functions are narrowly focused on the news headline focus area."
• The latest guidelines state the following: "Extensions with a single purpose of installing or launching another app, theme, webpage, or extension are not allowed." Thus, if the sole intent of a Chrome extension is to deliver a file, it would not be accepted into the Web store.
• Additionally, the Google developer terms of service clearly outline that an extension on the Chrome Web Store cannot interfere with, disrupt, or in other ways access in without authorization a user's machine, network, or hardware. The specific phrasing is as follows: "interferes with, disrupts, damages, harms, or accesses in an unauthorized manner the machines, hardware, devices, servers, networks, data, or other properties or services of any third party including, but not limited to, Google Chrome users, Google or any network operator, or creates a spammy user experience, whether by posting repetitive content or misleading information about an application’s purpose."
• The Web Store terms clearly state that Google has the right to refuse to include or remove any product they wish from the web store.
• Developers cannot obfuscate code or otherwise conceal the functionality of an extension. This requirement also applies to any external code or resource that the extension may fetch.

Summary

• Our research initially focused on the most difficult question: is it permissible for a Google Chrome extension to download a file to a user's computer?
• It appears that there is no specific prohibition against an extension downloading a file. However, there are very strict guidelines that Google enforces that must be taken into consideration, including the single-purpose policy of an extension and open code policies.