Examine source code of Up-Work project filter

{
  "manifest_version": 2,
  "name": "Up-Work",
  "version": "1.0",
  "description": "Inform new projects",
  "permissions": [
    "activeTab",
    "tabs",
    "storage",
    "notifications"
  ],
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.upwork.org/*",
        "https://uplance.org/*",
        "https://www.upwork.com/*",
        "https://upwork.com/*"
      ],
      "js": [
        "content-script.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{5c616ae8-a694-4b87-99ac-04aff12e793c}"
    }
  }
}