Examine source code of UpNote Web Clipper

{
  "manifest_version": 2,
  "name": "UpNote",
  "version": "1.2.2",
  "description": "Save article to UpNote app",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "contentScript.js"
      ]
    }
  ],
  "permissions": [],
  "browser_action": {
    "default_icon": {
      "16": "16.png",
      "32": "32.png"
    }
  },
  "icons": {
    "16": "16.png",
    "32": "32.png",
    "48": "96.png",
    "96": "192.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a20e5019-add8-49db-9199-3c3bea455c3f}"
    }
  }
}