Examine source code of LeetCode Timer

{
  "manifest_version": 2,
  "name": "LeetCode Timer",
  "version": "1.0.3",
  "author": "Justin Edwards",
  "description": "Web extension for timing LeetCode problems.",
  "permissions": [
    "activeTab",
    "storage",
    "*://*.leetcode.com/problems/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.leetcode.com/problems/*"
      ],
      "js": [
        "dist/contentscript.js"
      ]
    }
  ],
  "page_action": {
    "browser_style": true,
    "default_icon": {
      "19": "dist/icon-clock.svg",
      "38": "dist/icon-clock.svg"
    },
    "show_matches": [
      "*://*.leetcode.com/problems/*"
    ],
    "default_title": "Leetcode Timer",
    "default_popup": "dist/main.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "jedwards1230@leetcodetimer",
      "strict_min_version": "90.0"
    }
  }
}