Examine source code of Passwords 101

{
  "manifest_version": 2,
  "name": "Passwords 101",
  "description": "This extension generates a strong password based on a master password and an input, usually a url. This means you'll have a strong, unique, generated password for every website, yet only need to remember one password. The master password still needs to be a strong password, but that is your own responsibility.",
  "version": "1.4",
  "icons": {
    "48": "Icons/Shield48.png",
    "96": "Icons/Shield96.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "Icons/Shield16.png",
      "19": "Icons/Shield19.png",
      "32": "Icons/Shield32.png",
      "38": "Icons/Shield38.png",
      "64": "Icons/Shield64.png"
    },
    "default_title": "Generate password",
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "applications": {
    "gecko": {
      "id": "{13aaa695-c43c-4b0c-b267-31d06059e36e}"
    }
  }
}