Examine source code of vimkeybindings Improved

{
  "manifest_version": 2,
  "name": "vimkeybindings Improved",
  "description": "Vi(m) directional keybindings for Firefox.",
  "author": "Tartarus Kelvin",
  "version": "2.1.0",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script.js"
      ],
      "run_at": "document_start",
      "match_about_blank": true
    }
  ]
}