Examine source code of Browser JS Error Icon

{
  "name": "Browser JS Error Icon",
  "version": "1.1",
  "description": "Little icon to remind you that something gone wrong on the current tab.",
  "manifest_version": 2,
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "all_frames": true,
      "js": [
        "inject.js"
      ],
      "run_at": "document_start"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Chrome JS Error Icon",
    "default_popup": "popup.html"
  },
  "optional_permissions": [
    "<all_urls>"
  ]
}