Examine source code of A fast dictionary tool

{
  "manifest_version": 2,
  "name": "Dictionary Anywhere",
  "version": "1.0.0",
  "description": "Quickly look up word definitions from the popup or by right-clicking selected text.",
  "permissions": [
    "storage",
    "contextMenus",
    "tabs",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "Dictionary Anywhere",
    "default_popup": "popup.html"
  },
  "applications": {
    "gecko": {
      "id": "dictionary-anywhere@example.com"
    }
  }
}