Examine source code of SideScroll

{
  "manifest_version": 2,
  "name": "SideScroll",
  "version": "0.0.4",
  "description": "Scroll horizontally",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "sidescroll-16.png",
      "48": "sidescroll-48.png",
      "64": "sidescroll-64.png",
      "128": "sidescroll-128.png"
    }
  },
  "permissions": [
    "storage"
  ],
  "icons": {
    "16": "sidescroll-16.png",
    "48": "sidescroll-48.png",
    "64": "sidescroll-64.png",
    "128": "sidescroll-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f6e5c52a-50b1-424a-9b78-66cff3655a8b}"
    }
  }
}