Examine source code of Brief

{
  "name": "Brief",
  "version": "2.7.7",
  "author": "Denis Lisov",
  "homepage_url": "https://github.com/brief-rss/brief",
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "brief@mozdev.org",
      "strict_min_version": "78.0"
    }
  },
  "default_locale": "en",
  "permissions": [
    "<all_urls>",
    "menus",
    "bookmarks",
    "storage",
    "unlimitedStorage",
    "downloads",
    "tabs",
    "notifications",
    "webRequest",
    "webRequestBlocking"
  ],
  "background": {
    "page": "background.xhtml"
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": {
      "16": "icons/brief-icon-16.png",
      "32": "icons/brief-icon-32.png",
      "64": "icons/brief-icon-64.png"
    },
    "default_title": "Brief"
  },
  "page_action": {
    "default_icon": "icons/brief.svg",
    "default_title": "Subscribe",
    "default_popup": "/ui/subscribe/subscribe.xhtml",
    "browser_style": true
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+D"
      }
    }
  },
  "options_ui": {
    "page": "/ui/options/options.xhtml",
    "browser_style": true
  }
}