Disable GaiaAuthOffline test under MSan.

Flaky failures on the ChromeOS/MSan bot.

BUG=475516
TBR=xiyuan@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/1142963002

Cr-Commit-Position: refs/heads/master@{#330574}

chrome/browser/chromeos/login/login_browsertest.cc

@@ -334,7 +334,12 @@ IN_PROC_BROWSER_TEST_F(LoginTest, PRE_GaiaAuthOffline) {
       chromeos::kAccountsPrefShowUserNamesOnSignIn, false);
 }
 
-IN_PROC_BROWSER_TEST_F(LoginTest, GaiaAuthOffline) {
+#if defined(MEMORY_SANITIZER)
+#define MAYBE_GaiaAuthOffline DISABLED_GaiaAuthOffline
+#else
+#define MAYBE_GaiaAuthOffline GaiaAuthOffline
+#endif
+IN_PROC_BROWSER_TEST_F(LoginTest, MAYBE_GaiaAuthOffline) {
   PrepareOfflineLogin();
   content::WindowedNotificationObserver session_start_waiter(
       chrome::NOTIFICATION_SESSION_STARTED,