Examine source code of Media Cache Saver

{
  "manifest_version": 2,
  "name": "Media Cache Saver",
  "version": "1.0.0",
  "description": "Silently saves images/videos your browser already fetched (no extra bandwidth), per-site toggle, with a storage cap.",
  "browser_specific_settings": {
    "gecko": {
      "id": "media-cache-saver@local.extension",
      "strict_min_version": "78.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "<all_urls>",
    "webRequest",
    "webRequestBlocking",
    "downloads",
    "downloads.open",
    "storage",
    "tabs",
    "webNavigation"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Media Cache Saver",
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png",
      "48": "icons/icon48.png"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  }
}