Add missing dependency for bg scripts
BG snippet to fake fcommand execution
Revoke URL before removing <link>

- otherwise the link is no longer valid
Reminder
Construct the response object from scratch

- sending back the entire resolved-with object may result in circular
  references or have problems being converted to JSON.  Only include
  the properties needed in the background script.
Use namespaced function names for content script
Reflect new names in response from content script