Examine source code of Dark Mode - Night Eye

{
  "manifest_version": 2,
  "default_locale": "en",
  "name": "__MSG_extName__",
  "short_name": "Night Eye",
  "description": "__MSG_extDescription__",
  "homepage_url": "https://nighteye.app/",
  "author": "RAZORlabs",
  "icons": {
    "16": "res/icon/16.png",
    "48": "res/icon/48.png",
    "128": "res/icon/128.png"
  },
  "permissions": [
    "storage",
    "contextMenus",
    "activeTab",
    "tabs",
    "*://*/*"
  ],
  "web_accessible_resources": [
    "images/*",
    "css/*",
    "_locales/*",
    "js/browser-action/*",
    "html/browser-action/*",
    "js/content/cssom.js"
  ],
  "commands": {
    "toggle-current-website": {
      "suggested_key": {
        "default": "Alt+Shift+2",
        "mac": "Command+Shift+2"
      },
      "description": "__MSG_extToggleButton__"
    },
    "toggle-power-extension": {
      "suggested_key": {
        "default": "Alt+Shift+3",
        "mac": "Command+Shift+3"
      },
      "description": "Toggle on and off the extension"
    },
    "switch-filter-mode": {
      "suggested_key": {
        "default": "Alt+Shift+4",
        "mac": "Command+Shift+4"
      },
      "description": "Switch to filter mode"
    }
  },
  "externally_connectable": {
    "ids": [
      "c1b48edf-f3c7-4d56-aed1-b5dce75df3c6"
    ],
    "matches": [
      "<all_urls>"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "css/loading.css"
      ],
      "js": [
        "js/content/content.js"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "browser_action": {
    "default_icon": "res/icon/48.png",
    "default_popup": "html/browser-action/home.html",
    "default_title": "Night Eye"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "58.0",
      "id": "{7c6d56ed-2616-48f2-bfde-d1830f1cf2ed}"
    },
    "gecko_android": {
      "strict_min_version": "120.0"
    }
  },
  "version": "6.1.0"
}