Examine source code of Tooltip Jisyo

{
  "manifest_version": 2,
  "name": "ツールチップ辞書",
  "version": "0.0.6",
  "applications": {
    "gecko": {
      "id": "{cdd0ea72-a751-40d0-b610-926662a8b39b}"
    }
  },
  "description": "ツールチップで辞書を引く",
  "icons": {
    "256": "img/icon.png"
  },
  "page_action": {
    "browser_style": true,
    "default_icon": {
      "256": "img/icon.png"
    },
    "default_title": "Switch Engine!"
  },
  "background": {
    "scripts": [
      "dist/background.js"
    ]
  },
  "content_scripts": [
    {
      "run_at": "document_start",
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "dist/content.js"
      ],
      "css": [
        "dist/content.css"
      ]
    }
  ],
  "permissions": [
    "tabs",
    "storage",
    "https://*.weblio.jp/*",
    "https://*.goo.ne.jp/*"
  ],
  "options_ui": {
    "page": "dist/options_ui.html",
    "open_in_tab": true
  }
}