Examine source code of MyChronicles Extension

{
  "name": "MyChronicles Extension",
  "version": "1.5",
  "description": "keep track of what you read or watch online, all without lifting a finger",
  "author": "Lex Pan",
  "manifest_version": 3,
  "icons": {
    "128": "extension.png"
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "mychronicles@lexsprojects.ca"
    }
  },
  "action": {
    "default_popup": "index.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "contentScript.js"
      ]
    }
  ]
}