Examine source code of Sakura - Custom JS & CSS

{
  "manifest_version": 2,
  "name": "Sakura - Custom JS & CSS",
  "version": "1.0.0",
  "description": "User script manager that lets you inject your own JavaScript and CSS into websites matching URL patterns you define.",
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "storage",
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "contentScript.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "options_ui": {
    "page": "options.html",
    "browser_style": false,
    "open_in_tab": true
  },
  "browser_action": {
    "default_title": "Sakura - Custom JS & CSS"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "sakura@example.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}