Examine source code of Costumary Web Clipper

{
  "manifest_version": 2,
  "name": "Costumary Web Clipper",
  "description": "Save reference images from any page to your Costumary craft build boards. Right-click any image to clip it.",
  "version": "1.0.0",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "128": "icon/128.png"
  },
  "permissions": [
    "contextMenus",
    "storage",
    "activeTab",
    "scripting",
    "https://api.costumary.com/*",
    "https://*.costumary.com/*",
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "clipper@costumary.com",
      "data_collection_permissions": {
        "required": [
          "authenticationInfo"
        ],
        "optional": []
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Costumary Web Clipper",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://costumary.com/auth/extension*",
        "https://www.costumary.com/auth/extension*"
      ],
      "run_at": "document_start",
      "js": [
        "content-scripts/auth-relay.js"
      ]
    }
  ]
}