Examine source code of SaveTabs

{
  "manifest_version": 2,
  "name": "SaveTabs",
  "version": "1.2",
  "description": "Saves URLs of open tabs into a text file.",
  "icons": {
    "48": "icon.png",
    "96": "icon.png"
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "SaveTabs",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d72608af-8b25-44e3-b6bb-7885581fe987}"
    }
  }
}