Examine source code of TwineHacker

{
  "name": "TwineHacker",
  "version": "1.0.0",
  "description": "Allows you to change font/style; also adds cheats",
  "commands": {
    "enable_twine_hacker": {
      "suggested_key": {
        "default": "Ctrl+Shift+H"
      },
      "description": "Enable twine hacker"
    },
    "show_custom_globals": {
      "suggested_key": {
        "default": "Ctrl+Shift+K"
      },
      "description": "Show non-default globals"
    }
  },
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "icons": {
    "16": "Icons/16.png",
    "48": "Icons/48.png",
    "128": "Icons/128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "web_accessible_resources": [
    "twinehacker.js",
    "twinehacker.css",
    "show-custom-globals.js"
  ],
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{6bec78dc-3aa7-43a3-b073-0cc25dd957a3}"
    }
  }
}