Examine source code of eBird filter to bar chart

{
  "manifest_version": 2,
  "name": "eBird filter to bar chart",
  "version": "1.0.3",
  "content_scripts": [
    {
      "matches": [
        "https://review.ebird.org/admin/viewFilter.htm?*"
      ],
      "js": [
        "barchart.js"
      ]
    }
  ],
  "description": "eBird filter to bar chart",
  "homepage_url": "https://www.faintlake.com/eBird/extension/FilterBarChart/",
  "icons": {
    "48": "icons/48.png",
    "96": "icons/96.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9357f5c6-7882-425d-b6a6-82564f1072a4}"
    }
  }
}