Examine source code of Word Replacer

{
  "manifest_version": 2,
  "name": "Word Replacer",
  "version": "1.2",
  "description": "Replace words on webpages.",
  "permissions": [
    "tabs",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_script.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "128": "icon.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{dc9cb8d6-7ea6-4d17-8a6e-5a946df5d4ef}"
    }
  }
}