Examine source code of Nextify

{
  "manifest_version": 2,
  "name": "Nextify",
  "version": "1.7",
  "description": "goes to the next page on some manga sites",
  "homepage_url": "https://github.com/duqc/nextify",
  "icons": {
    "48": "icons/icon.png"
  },
  "content_scripts": [
    {
      "all_frames": true,
      "match_about_blank": true,
      "matches": [
        "*://*.chapmanganelo.com/*",
        "*://*.comick.io/comic/*",
        "*://*.mangakakalot.com/*",
        "*://*.opomanga.com/*"
      ],
      "run_at": "document_end",
      "js": [
        "ChangePage.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ba837081-5ec5-4d76-a7ec-95bd2f2a8ac6}"
    }
  }
}