Disable flaky DownloadNotificationTest.DownloadDangerousFile

tbr=estade@chromium.org

Bug: 822470
Change-Id: If9f4edf28d232113f6da357c7646feeef63d72cc
Reviewed-on: https://chromium-review.googlesource.com/965256Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543544}

chrome/browser/download/notification/download_notification_interactive_uitest.cc

@@ -357,7 +357,9 @@ IN_PROC_BROWSER_TEST_F(DownloadNotificationTest, DownloadFile) {
   EXPECT_FALSE(GetNotification(notification_id()));
 }
 
-IN_PROC_BROWSER_TEST_F(DownloadNotificationTest, DownloadDangerousFile) {
+// Flaky test: crbug/822470.
+IN_PROC_BROWSER_TEST_F(DownloadNotificationTest,
+                       DISABLED_DownloadDangerousFile) {
   GURL download_url(
       embedded_test_server()->GetURL("/downloads/dangerous/dangerous.swf"));