Examine source code of Text Decoder

{
  "manifest_version": 2,
  "name": "Text Decoder",
  "version": "1.0",
  "description": "選択した文字列をデコードして吹き出しで表示します。",
  "applications": {
    "gecko": {
      "id": "k.noguchi@mbsd.jp"
    }
  },
  "permissions": [
    "contextMenus",
    "activeTab",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "browser_action": {
    "default_popup": "options.html",
    "default_icon": {
      "16": "icon16.png",
      "48": "icon16.png",
      "128": "icon16.png"
    }
  },
  "content_security_policy": "script-src 'self'; object-src 'self'; style-src 'self' 'unsafe-inline'"
}