Examine source code of Salesforce Show Api Name

{
  "name": "Salesforce Show Api Name",
  "version": "1.2.1",
  "manifest_version": 2,
  "description": "Display Field & Object API Names on Detail Pages (LEX & Classic).",
  "homepage_url": "https://github.com/ChenZaichuang/salesforce_show_api_name",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "images/16.png",
    "32": "images/32.png",
    "48": "images/48.png",
    "128": "images/128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "images/16.png",
      "32": "images/32.png",
      "48": "images/48.png",
      "128": "images/128.png"
    },
    "default_title": "Show Salesforce Api Name"
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.force.com/*",
        "https://*.salesforce.com/*"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_end",
      "all_frames": false
    }
  ],
  "permissions": [
    "activeTab",
    "cookies",
    "https://*.force.com/*",
    "https://*.salesforce.com/*"
  ],
  "commands": {
    "showApiName": {
      "suggested_key": {
        "windows": "Alt+Shift+Z",
        "mac": "MacCtrl+Ctrl+Z",
        "linux": "Alt+Shift+Z",
        "chromeos": "Alt+Shift+Z"
      },
      "description": "Show Api Name"
    }
  }
}