Examine source code of Scroll by Button

{
  "manifest_version": 2,
  "name": "Scroll by Button",
  "version": "1.0",
  "description": "Scroll using large on-screen up/down arrows.",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_title": "Scroll by Button",
    "default_popup": "popup.html"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{50d3c850-7b2c-406a-ad43-2a1ea8e12224}"
    }
  }
}