Examine source code of Replacer

{
  "manifest_version": 2,
  "name": "Replacer",
  "version": "1.0.0",
  "author": "Alexander Shutau",
  "description": "__MSG_extension_description__",
  "default_locale": "en",
  "icons": {
    "16": "icons/icon-16x16.png",
    "48": "icons/icon-48x48.png",
    "128": "icons/icon-128x128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "replacer.js"
      ],
      "run_at": "document_start",
      "all_frames": true,
      "match_about_blank": true
    }
  ],
  "permissions": [
    "storage",
    "tabs",
    "unlimitedStorage",
    "<all_urls>"
  ],
  "commands": {
    "toggle_extension": {
      "description": "__MSG_toggle_extension__"
    },
    "toggle_website": {
      "description": "__MSG_toggle_website__"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "addon@replacer.app",
      "strict_min_version": "90.0"
    }
  },
  "browser_action": {
    "default_title": "Replacer",
    "default_popup": "popup/index.html",
    "default_icon": {
      "19": "icons/icon-19x19.png",
      "38": "icons/icon-38x38.png"
    }
  }
}