Examine source code of Seamless Sidekick

{
  "name": "__MSG_name__",
  "description": "__MSG_description__",
  "version": "1.3.4",
  "manifest_version": 2,
  "default_locale": "en",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "contextMenus",
    "http://localhost/*"
  ],
  "content_scripts": [
    {
      "run_at": "document_end",
      "matches": [
        "https://www.instagram.com/*"
      ],
      "js": [
        "instagram.js"
      ]
    }
  ],
  "icons": {
    "16": "/images/icon-16.png",
    "32": "/images/icon-32.png",
    "48": "/images/icon-48.png",
    "128": "/images/icon-128.png"
  }
}