Examine source code of NPM File Browser Package

{
  "manifest_version": 2,
  "name": "NPM Package File Browser",
  "version": "1.0.0",
  "description": "Adds a quick-access button on NPM package pages that lets you browse the contents of the package directly, making it easier to explore source files without leaving the page",
  "icons": {
    "16": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "content_scripts": [
    {
      "css": [
        "button.css"
      ],
      "js": [
        "content.js"
      ],
      "matches": [
        "https://www.npmjs.com/package/*"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9828de53-e255-4430-b06a-b00331e0e313}"
    }
  }
}