Examine source code of Key Jump keyboard navigation alphanumeric

{
  "manifest_version": 2,
  "name": "Key Jump keyboard navigation alphanumeric",
  "description": "Hit-a-Hint style keyboard navigation. No mouse needed to click on links and stuff. Fork with alphanumeric hints.",
  "version": "1",
  "author": "Kenneth Sundqvist <kenneth@kesu.se>",
  "homepage_url": "https://github.com/KennethSundqvist/key-jump-browser-extension",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "permissions": [
    "storage"
  ],
  "options_ui": {
    "page": "options.html",
    "chrome_style": true
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*",
        "ftp://*/*"
      ],
      "all_frames": false,
      "run_at": "document_start",
      "js": [
        "bootstrap-state.js",
        "content.js"
      ],
      "css": [
        "content.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "keyjump-alphanumeric@kesu.se"
    }
  }
}