Examine source code of Next Page Please

{
  "manifest_version": 2,
  "name": "Next Page Please",
  "version": "1.0",
  "description": "Use arrow keys to navigate between pages",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "nextpageplease@consantor.com"
    }
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png"
    },
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab",
    "storage",
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "navigator.js"
      ]
    }
  ]
}