Examine source code of Quick Dictionary 1ookup

{
  "manifest_version": 2,
  "name": "Quick Dictionary Lookup",
  "version": "1.0",
  "description": "Right-click any English word to look up its definition instantly.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "contextMenus",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "quick-dictionary-lookup@hqaddon"
    }
  }
}