cros: Fix external cache not updating.

chrome/browser/chromeos/extensions/external_cache.cc

Index: chrome/browser/chromeos/extensions/external_cache.cc
diff --git a/chrome/browser/chromeos/extensions/external_cache.cc b/chrome/browser/chromeos/extensions/external_cache.cc
index 8e8f205ac0ebd30200a1e14dc7fa9c4b13c5086c..d1cef41191c61a5a216c3a54cbfadfc608c6f99f 100644
--- a/chrome/browser/chromeos/extensions/external_cache.cc
+++ b/chrome/browser/chromeos/extensions/external_cache.cc
@@ -224,8 +224,8 @@ void ExternalCache::CheckCache() {
 
   // If request_context_ is missing we can't download anything.
   if (!downloader_ && request_context_.get()) {
-    downloader_.reset(
-        new extensions::ExtensionDownloader(this, request_context_.get()));
+    downloader_ = ChromeExtensionDownloaderFactory::CreateForRequestContext(
+        request_context_.get(), this);
   }
 
   cached_extensions_->Clear();