Examine source code of Digraphs for Firefox

{
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/dig-64.png",
    "default_popup": "popup.html",
    "default_title": "Digraphs"
  },
  "content_scripts": [
    {
      "js": [
        "digraphs.js"
      ],
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_start"
    }
  ],
  "description": "Vim-style digraphs for Firefox",
  "manifest_version": 2,
  "name": "Digraphs for Firefox",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "version": "1.1",
  "browser_specific_settings": {
    "gecko": {
      "id": "{b89b4b1c-4dcb-4891-87fa-314ae624df80}"
    }
  }
}