Examine source code of z-context

{
  "manifest_version": 2,
  "name": "z-context",
  "version": "1.0.4",
  "description": "A Chrome DevTools Extension that displays stacking contexts and z-index values in the elements panel",
  "author": "gwwar",
  "devtools_page": "devtools/index.html",
  "icons": {
    "16": "icons/icon_16.png",
    "48": "icons/icon_48.png",
    "72": "icons/icon_72.png",
    "96": "icons/icon_96.png",
    "128": "icons/icon_128.png",
    "144": "icons/icon_144.png",
    "192": "icons/icon_192.png"
  }
}