Examine source code of UI Previewer Button

{
  "name": "UI Previewer Button",
  "version": "0.3.1resigned1",
  "manifest_version": 2,
  "description": "Adds a preview button to a GitHub repo",
  "homepage_url": "http://gampleman.eu",
  "icons": {
    "16": "icons/Icon-16.png",
    "48": "icons/Icon-48.png",
    "128": "icons/Icon-128.png"
  },
  "permissions": [
    "https://github.com/*",
    "https://*.github.com/*",
    "contextMenus"
  ],
  "background": {
    "scripts": [
      "src/background.js"
    ],
    "persistent": false
  },
  "options_page": "src/options/index.html",
  "applications": {
    "gecko": {
      "id": "ui_previewer@rightscale.com"
    }
  }
}