Examine source code of Detect Enhanced Content

{
  "manifest_version": 2,
  "version": "1.3.1resigned1",
  "name": "Salsify Enhanced Content",
  "short_name": "Enhanced Content",
  "description": "Detects Salsify Enhanced Content on the page.",
  "author": "Salsify, Inc.",
  "homepage_url": "https://github.com/salsify/enhanced-content-extension",
  "icons": {
    "16": "app/public/icon-16.png",
    "32": "app/public/icon-32.png",
    "48": "app/public/icon-48.png",
    "96": "app/public/icon-96.png",
    "128": "app/public/icon-128.png",
    "150": "app/public/icon-150.png",
    "180": "app/public/icon-180.png",
    "192": "app/public/icon-192.png",
    "512": "app/public/icon-512.png"
  },
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_icon": {
      "32": "app/public/icon-disabled-32.png",
      "48": "app/public/icon-disabled-48.png",
      "96": "app/public/icon-disabled-96.png",
      "128": "app/public/icon-disabled-128.png"
    },
    "default_popup": "app/index.html",
    "default_title": "Enhanced Content"
  },
  "background": {
    "scripts": [
      "app/background.js"
    ]
  },
  "content_scripts": [
    {
      "js": [
        "app/content_script.js"
      ],
      "matches": [
        "https://www.walmart.com/ip/*",
        "https://www.bjs.com/product/*"
      ],
      "run_at": "document_end"
    }
  ],
  "web_accessible_resources": [
    "app/public/icon-32.svg"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{62f8d5a6-16c2-4c86-a1c8-e8739c72c12b}"
    }
  }
}