Examine source code of Dark Mode

{
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "all_frames": true,
      "run_at": "document_start",
      "js": [
        "inject/fallback.js",
        "inject/index.js"
      ],
      "match_about_blank": true
    },
    {
      "matches": [
        "<all_urls>"
      ],
      "all_frames": true,
      "run_at": "document_end",
      "js": [
        "inject/service.js",
        "inject/filter.js",
        "inject/theme.js",
        "inject/eload.js"
      ]
    }
  ],
  "commands": {
    "toggle": {
      "suggested_key": {
        "default": "Alt+Shift+D"
      },
      "description": "__MSG_toggle_extension__"
    },
    "switchEngine": {
      "description": "__MSG_theme_generation_mode__"
    },
    "addSite": {
      "suggested_key": {
        "default": "Alt+Shift+A"
      },
      "description": "__MSG_toggle_current_site__"
    }
  },
  "browser_specific_settings": {
    "gecko_android": {},
    "gecko": {
      "strict_min_version": "78.0",
      "id": "{41b57c90-eb8b-7c9b-4510-f6cf48908edb}"
    }
  },
  "name": "Lights Off - Free",
  "default_locale": "en_US",
  "icons": {
    "16": "icon.png",
    "48": "icon.png",
    "128": "icon.png"
  },
  "manifest_version": 2,
  "version": "4.9.3",
  "background": {
    "page": "background/index.html"
  },
  "content_security_policy": "script-src 'self' 'unsafe-eval';  object-src 'self';",
  "browser_action": {
    "default_title": "Lights Off - Free",
    "default_icon": {
      "19": "icon.png",
      "38": "icon.png"
    },
    "default_popup": "ui/popup/index.html"
  },
  "permissions": [
    "webRequest",
    "contextMenus",
    "webNavigation",
    "webRequestBlocking",
    "alarms",
    "storage",
    "tabs",
    "theme",
    "<all_urls>",
    "*://*/*"
  ],
  "description": "__MSG_extension_description__"
}