Examine source code of Tab Notes

{
  "applications": {
    "gecko": {
      "id": "note-tab@wildsky.cc",
      "strict_min_version": "54.0a1"
    }
  },
  "icons": {
    "48": "icons/48.png",
    "96": "icons/96.png",
    "128": "icons/128.png",
    "256": "icons/256.png"
  },
  "manifest_version": 2,
  "name": "Tab Notes",
  "version": "3.2.0",
  "description": "Allow you to write anything in new tab",
  "permissions": [
    "storage",
    "unlimitedStorage"
  ],
  "chrome_url_overrides": {
    "newtab": "newtab.html"
  },
  "browser_action": {
    "browser_style": true,
    "default_icon": "icons/48.png",
    "default_title": "Tab notes",
    "default_popup": "newtab.html"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Y"
      }
    }
  }
}