Examine source code of Now TV Background Removal

{
  "manifest_version": 2,
  "name": "Now TV Background Removal",
  "version": "1.0",
  "description": "A Firefox extension to remove background color from NOW TV controls.",
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://www.nowtv.com/gb/watch/playback/live/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ab6078f5-8693-45fa-bd8f-76b29943678a}"
    }
  }
}