Examine source code of Download Bar

{
  "manifest_version": 2,
  "name": "Download Bar",
  "version": "1.0",
  "description": "Manage your downloads easily with a sleek status bar interface.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [
    "downloads",
    "downloads.shelf"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{8d16fa47-9bee-40ef-9202-a534a6a53dbe}"
    }
  }
}