Examine source code of Tab Closer

{
  "manifest_version": 2,
  "name": "Tab Closer",
  "version": "1.0.1",
  "description": "Closes tabs after they finish loading if they match a list of URLs (like redirection links to native apps)",
  "permissions": [
    "tabs",
    "storage",
    "webNavigation"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "browser_action": {
    "default_title": "Tab Closer",
    "default_icon": "icon-48.png"
  },
  "icons": {
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "tab-closer@pendowski.com",
      "strict_min_version": "58.0"
    }
  },
  "content_security_policy": "default-src 'self'"
}