Examine source code of Cambridge Dictionary

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Cambridge Dictionary",
  "version": "1.3resigned1",
  "manifest_version": 2,
  "description": "Look up Cambridge Advanced Learner's Dictionary for the selected text",
  "icons": {
    "16": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "browser_action": {
    "default_icon": "icon.png"
  },
  "background": {
    "scripts": [
      "cambridge.js"
    ]
  },
  "permissions": [
    "activeTab",
    "contextMenus"
  ],
  "author": "Quy Nguyen",
  "browser_specific_settings": {
    "gecko": {
      "id": "{4d746711-e83b-4346-9850-ef5a9daf60f2}"
    }
  }
}