Examine source code of drupal-patch-color

{
  "manifest_version": 2,
  "name": "drupal-patch-color",
  "version": "1.5.6",
  "description": "Add coloration for drupal.org patch",
  "icons": {
    "48": "icons/icon48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.drupal.org/*.diff",
        "*://*.drupal.org/*.patch",
        "*://git.drupalcode.org/*.patch"
      ],
      "js": [
        "scripts/script.js"
      ],
      "css": [
        "styles/css/styles.css"
      ]
    }
  ]
}