Examine source code of OffTheShelf

{
  "name": "OffTheShelf",
  "version": "1.6.21resigned1",
  "description": "オンライン書店のページに価格比較を自動表示します。対応書店は、Amazon.co.jp、ブックオフオンライン、ネットオフ、駿河屋です。",
  "content_security_policy": "script-src 'self'; object-src 'self'; style-src 'self'",
  "background": {
    "scripts": [
      "libs/jquery-3.0.0.min.js",
      "background.js"
    ],
    "persistent": false
  },
  "icons": {
    "128": "icons/icon128.png"
  },
  "manifest_version": 2,
  "content_scripts": [
    {
      "all_frames": true,
      "matches": [
        "*://*.amazon.co.jp/*"
      ],
      "css": [
        "amazon.user.css"
      ],
      "js": [
        "libs/jquery-3.0.0.min.js",
        "amazookoff.js",
        "amazon.user.js"
      ],
      "run_at": "document_end"
    },
    {
      "all_frames": true,
      "matches": [
        "*://*.bookoffonline.co.jp/*"
      ],
      "css": [
        "bookoff.user.css"
      ],
      "js": [
        "libs/jquery-3.0.0.min.js",
        "amazookoff.js",
        "bookoff.user.js"
      ],
      "run_at": "document_end"
    },
    {
      "all_frames": true,
      "matches": [
        "*://*.netoff.co.jp/*"
      ],
      "css": [
        "netoff.user.css"
      ],
      "js": [
        "libs/jquery-3.0.0.min.js",
        "amazookoff.js",
        "netoff.user.js"
      ],
      "run_at": "document_end"
    },
    {
      "all_frames": true,
      "matches": [
        "*://*.suruga-ya.jp/*"
      ],
      "css": [
        "surugaya.user.css"
      ],
      "js": [
        "libs/jquery-3.0.0.min.js",
        "amazookoff.js",
        "surugaya.user.js"
      ],
      "run_at": "document_end"
    }
  ],
  "homepage_url": "http://booksbar.jp/",
  "permissions": [
    "*://*.amazon.co.jp/",
    "*://*.bookoffonline.co.jp/*",
    "*://*.netoff.co.jp/*",
    "*://*.suruga-ya.jp/*",
    "*://*.booksbar.jp/*",
    "*://lab.sugimototatsuo.com/*",
    "storage",
    "unlimitedStorage"
  ],
  "web_accessible_resources": [
    "images/amazon.png",
    "images/bookoffonline.png",
    "images/netoff.png",
    "images/surugaya.jpg"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "offtheshelf@booksbar.jp"
    }
  }
}