Disable newly flaky test MediaAppPreferredOverChromeApps

Bug: 1090432
Change-Id: I00eea4851b95669ffa5e6824d2eecf1366f65dbc
Tbr: tapted@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2226972Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774327}

chrome/browser/chromeos/file_manager/file_tasks_browsertest.cc

@@ -417,8 +417,9 @@ IN_PROC_BROWSER_TEST_F(FileTasksBrowserTest, InstalledAppsAreImplicitDefaults) {
 
 // If the media app is enabled, it will be preferred over a chrome app with a
 // specific extension, unless that app is set default via prefs.
+// Flaky: http://crbug.com/1090432
 IN_PROC_BROWSER_TEST_F(FileTasksBrowserTestWithMediaApp,
-                       MediaAppPreferredOverChromeApps) {
+                       DISABLED_MediaAppPreferredOverChromeApps) {
   Profile* profile = browser()->profile();
   auto extension = InstallTiffHandlerChromeApp(profile);
   TestExpectationsAgainstDefaultTasks({{"tiff", kMediaAppId}});