Examine source code of Follow Mastodon User

{
  "manifest_version": 2,
  "name": "Follow Mastodon User",
  "description": "Adds an address bar button (page action) that makes it easy to follow Mastodon users",
  "version": "1.0",
  "author": "Joshka",
  "homepage_url": "https://github.com/joshka/follow-mastodon-user-webextension",
  "icons": {
    "48": "mastodon-logo-purple.svg",
    "64": "mastodon-logo-purple.svg",
    "96": "mastodon-logo-purple.svg"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e87e8dab-396a-4dbd-966d-a2e93932ea6a}"
    }
  },
  "permissions": [
    "<all_urls>",
    "activeTab",
    "tabs",
    "storage",
    "identity"
  ],
  "background": {
    "scripts": [
      "background-script.js"
    ]
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true,
    "chrome_style": true
  },
  "page_action": {
    "browser_style": true,
    "default_icon": "mastodon-logo-purple.svg",
    "default_popup": "page-action.html",
    "default_title": "Follow Mastodon User",
    "show_matches": [
      "https://*/@*"
    ]
  }
}