Examine source code of Gmail Quick Forward Reply

{
  "manifest_version": 2,
  "name": "Gmail Quick Response",
  "version": "1.11",
  "description": "Quickly insert standard reply and add specific CC in Gmail",
  "applications": {
    "gecko": {
      "id": "{e5ee7a88-232b-4ee8-9f7a-c8fce6cee0cb}",
      "strict_min_version": "120.0"
    }
  },
  "permissions": [
    "activeTab",
    "storage",
    "*://mail.google.com/*"
  ],
  "browser_action": {
    "default_icon": {
      "16": "icon16.png",
      "48": "icon48.png",
      "128": "icon128.png"
    },
    "default_title": "Gmail Quick Response"
  },
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "content_scripts": [
    {
      "matches": [
        "*://mail.google.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  }
}