Examine source code of TestRail TestCasesCount

{
  "description": "Getting count of Test Cases found by filter",
  "manifest_version": 2,
  "name": "TestRail TestCasesCount",
  "version": "1.2resigned1",
  "homepage_url": "https://github.com/cernyjan/TestRail-TestCasesCount",
  "icons": {
    "48": "icons/calculator-48.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/calculator-48.png",
      "32": "icons/calculator-48.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://*/*"
      ],
      "js": [
        "jquery-3.2.1.min.js",
        "TestRail-TestCasesCount.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{71892f18-7f9f-45f5-b0a9-0a9804820794}"
    }
  }
}