Cleanup ExtensionDownloadsEventRouter on download manager shutdown

chrome/browser/download/chrome_download_manager_delegate.cc

Index: chrome/browser/download/chrome_download_manager_delegate.cc
diff --git a/chrome/browser/download/chrome_download_manager_delegate.cc b/chrome/browser/download/chrome_download_manager_delegate.cc
index 5fcf446f1d0a6b579f3374b55c58478d191fbc0d..fc95cbf4f129ef68b2e2c50d187f02548b1c81d1 100644
--- a/chrome/browser/download/chrome_download_manager_delegate.cc
+++ b/chrome/browser/download/chrome_download_manager_delegate.cc
@@ -144,6 +144,9 @@ void ChromeDownloadManagerDelegate::SetDownloadManager(DownloadManager* dm) {
 void ChromeDownloadManagerDelegate::Shutdown() {
   download_history_.reset();
   download_prefs_.reset();
+#if !defined(OS_ANDROID)
+  extension_event_router_.reset();
+#endif
 }
 
 DownloadId ChromeDownloadManagerDelegate::GetNextId() {