Dark mode for PDF files

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_popup": "html/popup.html",
    "default_title": "__MSG_name__"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "js/content.js"
      ],
      "all_frames": true,
      "run_at": "document_end"
    }
  ],
  "content_security_policy": "script-src 'self' https://www.google-analytics.com; object-src 'self'",
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "default_locale": "en",
  "manifest_version": 2,
  "name": "__MSG_name__",
  "description": "__MSG_description__",
  "permissions": [
    "<all_urls>",
    "storage"
  ],
  "version": "0.9.5"
}