Examine source code of FeedbackPanda

{
  "manifest_version": 2,
  "author": "Arvid Kahl <arvid@feedbackpanda.com>",
  "name": "FeedbackPanda",
  "homepage_url": "https://www.feedbackpanda.com",
  "version": "1.21.36",
  "description": "For Online ESL Teachers: Spend less time writing Feedback and more time doing what you love.",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "icon_16.png",
    "48": "icon_48.png",
    "128": "icon_128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.feedbackpanda.com/*",
        "*://www.feedbackpanda.com/*",
        "*://app.feedbackpanda.com/*",
        "*://www.vipkidteachers.com/*",
        "*://www.vipkid.com/*",
        "*://t.vipkidteachers.com/*",
        "*://t.vipkid.com.cn/*",
        "*://teacher.vipkid.com.cn/*",
        "*://t.mmears.com/*",
        "*://www.aizhuanjiao.com/t/*",
        "*://teacher.landi.com/*",
        "*://consultant.tutorabc.com/*",
        "*://teach.tutorabc.com.cn/*",
        "*://teacher.gogokid.com/*",
        "*://www.dadaabc.com/apps/*",
        "*://teacher.hujiang.com/*",
        "*://*.vipx.com/*"
      ],
      "js": [
        "jquery-3.1.1.js",
        "content.js"
      ]
    }
  ],
  "browser_action": {
    "default_title": "FeedbackPanda Integration",
    "default_icon": {
      "16": "icon_16.png",
      "48": "icon_48.png",
      "128": "icon_128.png"
    }
  },
  "permissions": [
    "*://*/*"
  ],
  "applications": {
    "gecko": {
      "id": "{15a59768-725c-4640-8bc8-be7502df2917}"
    }
  }
}