Examine source code of Video Thumbnail Generator

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "version": "1.0",
  "description": "__MSG_extensionDescription__",
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_action": {
    "default_icon": {
      "48": "icons/icon.png"
    },
    "default_title": "__MSG_extensionName__",
    "default_popup": "popup/popup.html"
  },
  "permissions": [
    "downloads",
    "activeTab",
    "storage"
  ],
  "background": {
    "scripts": [
      "background/background.js"
    ]
  },
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": true
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content/contentScript.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{4e18837e-dd84-409b-b4e6-b87158a55978}"
    }
  }
}