Examine source code of Opal Notes

{
  "manifest_version": 2,
  "name": "Opal - Advanced Note-Taking",
  "version": "1.4",
  "description": "Opal: sophisticated note-taking featuring unique aesthetic and advanced capabilities.",
  "icons": {
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "activeTab",
    "storage",
    "contextMenus",
    "tabs",
    "webRequestBlocking"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "browser-polyfill.js",
        "save.js",
        "app.js"
      ],
      "css": [
        "style.css"
      ]
    }
  ],
  "browser_action": {
    "default_icon": {
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0db7ba46-d9dc-4894-9e92-a57281949d3e}"
    }
  }
}