Examine source code of vimode

{
  "manifest_version": 2,
  "name": "vimode",
  "version": "1.1.2",
  "description": "vimode is an Add-on that let us to use vi-like operations on Firefox.",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "permissions": [
    "sessions"
  ],
  "background": {
    "scripts": [
      "background-script.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script.js"
      ]
    }
  ]
}