Examine source code of Layout Debugger

{
  "manifest_version": 2,
  "name": "Layout Debugger",
  "short_name": "Layout Debugger",
  "description": "Chrome extension for highlighting DOM elements to better debug layout issues",
  "version": "1.7",
  "author": "Chris Snowden",
  "icons": {
    "19": "images/icon19dark.png",
    "38": "images/icon38dark.png",
    "128": "images/icon128dark.png"
  },
  "browser_action": {
    "default_icon": {
      "19": "images/icon19dark.png",
      "38": "images/icon38dark.png"
    },
    "default_title": "Toggle highlighter"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "highlight.js"
      ]
    }
  ],
  "permissions": [
    "activeTab"
  ],
  "web_accessible_resources": [
    "images/icon19dark.png",
    "images/icon38dark.png",
    "images/icon128dark.png",
    "highlight.js"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{624f9a0a-b329-447c-9bd5-cd51d1cdd0e0}"
    }
  }
}