Examine source code of CSS Diagnostics

{
  "name": "CSS Diagnostics",
  "version": "1.0",
  "description": "Highlight potentially invalid or erroneous HTML markup",
  "homepage_url": "https://github.com/scriptex/css-diagnostics",
  "manifest_version": 2,
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": "assets/icon.png"
  },
  "icons": {
    "16": "assets/icon-16x16.png",
    "32": "assets/icon-32x32.png",
    "48": "assets/icon-48x48.png",
    "128": "assets/icon-128x128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    },
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "style.css"
      ],
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "activeTab",
    "storage",
    "contextMenus"
  ],
  "optional_permissions": [
    "http://*/*",
    "https://*/*"
  ]
}