Mark some sync tests as flaky.

chrome/test/live_sync/single_client_live_passwords_sync_test.cc

Index: chrome/test/live_sync/single_client_live_passwords_sync_test.cc
diff --git a/chrome/test/live_sync/single_client_live_passwords_sync_test.cc b/chrome/test/live_sync/single_client_live_passwords_sync_test.cc
index ba56e02a7c74b74a8363a5f9fe16c75b7c506a66..149763d1bc82b41041fb57bc341b48f0aa57d3d6 100644
--- a/chrome/test/live_sync/single_client_live_passwords_sync_test.cc
+++ b/chrome/test/live_sync/single_client_live_passwords_sync_test.cc
@@ -8,7 +8,8 @@
 
 using webkit_glue::PasswordForm;
 
-IN_PROC_BROWSER_TEST_F(SingleClientLivePasswordsSyncTest, Sanity) {
+// TODO(rsimha): See http://crbug.com/78840.
+IN_PROC_BROWSER_TEST_F(SingleClientLivePasswordsSyncTest, FLAKY_Sanity) {
   ASSERT_TRUE(SetupSync()) << "SetupSync() failed.";
 
   PasswordForm form = CreateTestPasswordForm(0);