Examine source code of Reddit Hide Viewed Posts

{
  "manifest_version": 2,
  "name": "RedditViewsHidder",
  "version": "1.2",
  "description": "Hide viewed reddit posts",
  "browser_specific_settings": {
    "gecko": {
      "id": "{7af24c85-122c-4ea7-9f2a-96836496dc34}"
    }
  },
  "icons": {
    "48": "icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.reddit.com/*"
      ],
      "js": [
        "redditviewshidder.js"
      ]
    }
  ],
  "permissions": [
    "storage"
  ]
}