Examine source code of Btgf ID Overlay

{
  "manifest_version": 2,
  "name": "Btgf ID Overlay",
  "version": "1.0",
  "description": "Finds Wowhead IDs and overlays them onto an existing icons (Wowhead, EightyUpgrades(WIP), Wowsims(WIP))",
  "icons": {
    "48": "btgf48.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://*.wowhead.com/*"
      ],
      "js": [
        "wowhead.js"
      ]
    },
    {
      "matches": [
        "https://eightyupgrades.com/*"
      ],
      "js": [
        "eightyupgrades.js"
      ]
    },
    {
      "matches": [
        "https://wowsims.github.io/*"
      ],
      "js": [
        "wowsims.js"
      ]
    }
  ],
  "browser_action": {
    "default_icon": "btgf48.png",
    "default_title": "Btgf Icon Overlay"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{04601384-31a9-41d8-ad89-8caf4d95ae15}"
    }
  }
}