Examine source code of RotoTracker Sync

{
  "manifest_version": 2,
  "name": "RotoTracker Sync",
  "short_name": "RotoTracker",
  "version": "3.1.0",
  "description": "Keep your DFS entry history results up to date with RotoTracker Sync.",
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "applications": {
    "gecko": {
      "id": "rtsync@rototracker.com",
      "strict_min_version": "48.0"
    }
  },
  "homepage_url": "https://rototracker.com/",
  "permissions": [
    "tabs",
    "storage",
    "https://rototracker.com/*",
    "https://www.fanduel.com/",
    "https://*.yahoo.com/",
    "https://www.draftday.com/"
  ],
  "browser_action": {
    "default_icon": {
      "19": "images/icon19.png"
    },
    "default_title": "RotoTracker Sync"
  },
  "background": {
    "scripts": [
      "scripts/events.js"
    ],
    "persistent": false
  }
}