Examine source code of Quick Reply

{
  "manifest_version": 2,
  "name": "Quick Reply",
  "version": "1.1.2",
  "description": "Quickly reply on web whatsapp with a keyboard shortcut",
  "short_name": "Short Sample Name",
  "browser_specific_settings": {
    "gecko": {
      "id": "kousikr26@gmail.com",
      "strict_min_version": "42.0"
    }
  },
  "browser_action": {
    "default_icon": "logo.png",
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "https://web.whatsapp.com/"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "commands": {
    "reply-out": {
      "suggested_key": {
        "default": "Alt+W",
        "mac": "Alt+W"
      },
      "description": "Reply to sent message"
    },
    "reply-out-back": {
      "suggested_key": {
        "default": "Alt+Shift+W",
        "mac": "Alt+Shift+W"
      },
      "description": "Reply to sent message(toggle backward)"
    },
    "reply-in": {
      "suggested_key": {
        "default": "Alt+Q",
        "mac": "Alt+Q"
      },
      "description": "Reply to received message"
    },
    "reply-in-back": {
      "suggested_key": {
        "default": "Alt+Shift+Q",
        "mac": "Alt+Shift+Q"
      },
      "description": "Reply to received message(toggle backward)"
    }
  }
}