Examine source code of SepiaToner

{
  "manifest_version": 2,
  "name": "SepiaToner",
  "version": "1.0.0",
  "description": "Adds sepia tone to all web pages to give a old style look and feel",
  "icons": {
    "256": "icons/icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "/content_script.js"
      ]
    }
  ],
  "browser_action": {
    "browser_style": true,
    "default_icon": {
      "256": "icons/icon.png"
    },
    "default_title": "SepiaToner",
    "default_popup": "/popup.html"
  },
  "permissions": [
    "storage"
  ]
}