Examine source code of FlickrDash

{
  "manifest_version": 2,
  "name": "FlickrDash",
  "version": "1.1",
  "description": "Adds some useful links to Flickr.",
  "content_scripts": [
    {
      "matches": [
        "*://*.flickr.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ]
}