Examine source code of EncounterBeyond

{
  "name": "EncounterBeyond",
  "description": "A simple extension to send digital rolls from D&D Beyond to EncounterPlus",
  "manifest_version": 2,
  "version": "0.9",
  "browser_specific_settings": {
    "gecko": {
      "id": "encounterbeyond@play5e.online"
    }
  },
  "icons": {
    "48": "encounter48.png",
    "96": "encounter96.png"
  },
  "permissions": [
    "*://*/api/messages",
    "storage"
  ],
  "options_ui": {
    "page": "options.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "page_action": {
    "default_icon": {
      "19": "encounter19.png",
      "38": "encounter38.png"
    },
    "default_title": "EncounterBeyond",
    "browser_style": true,
    "default_popup": "options.html",
    "show_matches": [
      "https://*.dndbeyond.com/profile/*/characters/*",
      "https://*.dndbeyond.com/characters/*"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.dndbeyond.com/profile/*/characters/*",
        "https://*.dndbeyond.com/characters/*"
      ],
      "run_at": "document_end",
      "js": [
        "rollgrabber.js"
      ]
    },
    {
      "matches": [
        "*://*/client/"
      ],
      "run_at": "document_end",
      "js": [
        "hostgrab.js"
      ]
    }
  ]
}