Examine source code of Twitch Watchtime Tracker

{
  "manifest_version": 2,
  "name": "watchtime-tracker",
  "version": "1.2.0",
  "description": "Tracks the time you watch a Twitch streams / category",
  "icons": {
    "48": "icons/48.png"
  },
  "permissions": [
    "storage"
  ],
  "web_accessible_resources": [
    "popup/popup.html",
    "popup/popup.js",
    "popup/popup.css"
  ],
  "options_ui": {
    "page": "index.html",
    "browser_style": true
  },
  "browser_action": {
    "default_icon": {
      "19": "icons/19.png",
      "38": "icons/38.png"
    },
    "default_title": "watchtime-tracker",
    "default_popup": "popup/popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.twitch.tv/*"
      ],
      "js": [
        "background/script.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ec59d2e4-1cd9-432a-9df9-d74faaae9881}"
    }
  }
}