Examine source code of Smart Selection

{
  "manifest_version": 2,
  "name": "Smart Selection Search",
  "description": "Smart Selection Search is a free extension for quickly manipulating selected text on the browser.",
  "version": "1.0.0",
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "index.html"
  },
  "icons": {
    "128": "icon_128.png"
  },
  "permissions": [
    "<all_urls>",
    "tabs"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "main.css"
      ],
      "js": [
        "selection.js"
      ],
      "all_frames": true
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{21dfedc1-47f1-4112-a7d2-6f2adddab879}"
    }
  }
}