Examine source code of Leetcode: hide testcase

{
  "manifest_version": 2,
  "name": "Leetcode: hide testcase",
  "version": "1.0.1",
  "description": "This extension helps hide the failed testcase while practicing on Leetcode",
  "icons": {
    "16": "assets/img16.png",
    "36": "assets/img36.png",
    "48": "assets/img48.png",
    "64": "assets/img64.png",
    "128": "assets/img128.png"
  },
  "permissions": [
    "tabs",
    "webRequest",
    "*://leetcode.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": {
      "48": "assets/img48.png"
    },
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://leetcode.com/problems/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "styles.css"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a0f377a8-9dd2-4ec2-ae1a-aa791ee59124}"
    }
  }
}