Examine source code of Safely Password Manager

{
  "manifest_version": 2,
  "name": "Safely Password Manager",
  "short_name": "safely",
  "description": "An extension to support Safely Password Manager in your browser!",
  "version": "0.8resigned1",
  "applications": {
    "gecko": {
      "id": "safely@wunderweiss.com"
    }
  },
  "icons": {
    "16": "icons/icon16px.png",
    "48": "icons/icon48px.png",
    "128": "icons/icon128px.png"
  },
  "background": {
    "page": "background.html"
  },
  "page_action": {
    "default_icon": "icon.png",
    "default_title": "safely",
    "default_popup": "popup.html"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "<all_urls>",
    "webNavigation",
    "clipboardRead",
    "clipboardWrite",
    "notifications"
  ],
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "thirdparty/jquery-3.3.1.min.js",
        "thirdparty/hotkeys.min.js",
        "contentscript.js"
      ],
      "run_at": "document_end"
    }
  ]
}