1. A method for running an operating system on a device, the method comprising: receiving, from an instance of a web browser, an operating system service request; running the operating system service request by the operating system, wherein the operating system service request requests access to a resource of the operating system; retrieving a security context for the resource from a file system of the operating system; and applying an access control security policy based upon the security context and based upon information regarding the instance of a web browser, wherein the security policy grants access to the resource if a property or properties of the security context match a property or properties of the instance of the web browser.