Examine source code of Reddit Activity Viewer

{
  "manifest_version": 2,
  "name": "Reddit Activity Viewer",
  "version": "3.0",
  "description": "Find you who you're talking to, get the selected users account informations such as: Creation date, total posts and comments, Active period, there most active subreddits, and there best and worst takes.",
  "permissions": [
    "activeTab",
    "https://*.reddit.com/*",
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icon.png"
    }
  },
  "icons": {
    "48": "icon.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.reddit.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{eb1449c9-7a3d-4387-964f-69045a0ce693}"
    }
  }
}