Examine source code of Lazy Mirror

{
  "manifest_version": 2,
  "name": "Lazy Mirror",
  "version": "1.0",
  "description": "Press a hotkey to randomly mirror images on the page horizontally or vertically.",
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_action": {
    "default_title": "Lazy Mirror",
    "default_icon": "icon.png"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5851e2b9-8059-4956-b59c-69dce7faf497}"
    }
  }
}