Examine source code of Ext JS 3 DevTools

{
  "manifest_version": 3,
  "default_locale": "ru",
  "name": "Ext JS 3 DevTools",
  "description": "__MSG_extensionDescription__",
  "author": "Захаров Александр",
  "homepage_url": "https://github.com/3axapp/ext-js-3-devtools",
  "version": "1.7.2.0",
  "content_security_policy": {
    "extension_pages": "script-src 'self'; object-src 'self'"
  },
  "icons": {
    "16": "assets/icon_16.png",
    "32": "assets/icon_32.png",
    "48": "assets/icon_48.png",
    "128": "assets/icon_128.png"
  },
  "permissions": [
    "storage",
    "scripting",
    "activeTab",
    "alarms"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "backend.js"
      ]
    }
  ],
  "devtools_page": "devtools.html",
  "web_accessible_resources": [
    {
      "resources": [
        "page.js"
      ],
      "matches": [
        "<all_urls>"
      ],
      "extension_ids": []
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "ext-js-3-devtools@0x3a.xyz"
    }
  }
}