Examine source code of Batch Downloader

{
  "manifest_version": 2,
  "name": "Batch Downloader",
  "description": "Collects all media file URLs on the page and lets you download them in batch",
  "version": "1.1",
  "icons": {
    "64": "icons/icon-64.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "activeTab",
    "downloads"
  ],
  "browser_action": {
    "default_icon": "icons/icon-64.png",
    "default_title": "Batch Downloader",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{59f1aa00-ed61-4e2e-912e-fb92557a63dc}",
      "strict_min_version": "100.0"
    }
  }
}