Examine source code of Library+

{
  "manifest_version": 2,
  "name": "__MSG_extName__",
  "description": "__MSG_extDescription__",
  "version": "0.1.5",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "default_locale": "ja",
  "permissions": [
    "storage",
    "https://booth.pm/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "library-plus@metarecipe.jp",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.booth.pm/items/*",
        "*://booth.pm/*/items/*"
      ],
      "js": [
        "content-scripts/item-page.js"
      ]
    },
    {
      "matches": [
        "*://accounts.booth.pm/library*"
      ],
      "js": [
        "content-scripts/library.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "content-scripts/library.css"
  ]
}