Examine source code of PassCell

{
  "name": "PassCell",
  "version": "1.9.11",
  "manifest_version": 2,
  "description": "Generate and manage passwords",
  "icons": {
    "48": "icons/w48.png"
  },
  "permissions": [
    "storage",
    "activeTab",
    "<all_urls>",
    "contextMenus"
  ],
  "background": {
    "scripts": [
      "util.js",
      "background.js"
    ]
  },
  "browser_action": {
    "browser_style": true,
    "default_popup": "popup.html",
    "default_icon": "icons/32.png",
    "default_title": "Manage password of this site"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f166acd7-f3f0-45ce-a6ed-963843670f4a}"
    }
  }
}