Examine source code of ToN tracker+

{
  "manifest_version": 2,
  "name": "ToN tracker+",
  "version": "1.14.3",
  "description": "Adds new features to the (already amazing) ToN tracker.",
  "permissions": [
    "activeTab",
    "scripting",
    "https://tontrack.me/*"
  ],
  "web_accessible_resources": [
    "notif.mp3",
    "streakBreak.mp3",
    "bell_off.png",
    "bell_on.png",
    "discord_icon.png",
    "inject.js"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "128": "favicon.png"
    }
  },
  "icons": {
    "32": "favicon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://tontrack.me/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{11c81146-3827-4b2c-8e18-a8b731f115cf}"
    }
  }
}