Disable a test in TwoClientPreferencesSyncTest on CrOS

TwoClientPreferencesSyncTest.SingleClientEnabledEncryptionBothChanged is flaky
on ChromeOS bots. This disables it.

TBR=vitaliii@chromium.org
NOTRY=true

Bug: 873902
Change-Id: I72b3692746942c7c8e4cb58e06bc9b7817402f85
Reviewed-on: https://chromium-review.googlesource.com/1173201Reviewed-by: Makoto Shimazu <shimazu@chromium.org>
Commit-Queue: Makoto Shimazu <shimazu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582798}

chrome/browser/sync/test/integration/two_client_preferences_sync_test.cc

@@ -7,6 +7,7 @@
 #include "base/guid.h"
 #include "base/macros.h"
 #include "base/strings/stringprintf.h"
+#include "build/build_config.h"
 #include "chrome/browser/sync/test/integration/preferences_helper.h"
 #include "chrome/browser/sync/test/integration/profile_sync_service_harness.h"
 #include "chrome/browser/sync/test/integration/sync_integration_test_util.h"
@@ -121,8 +122,17 @@ IN_PROC_BROWSER_TEST_F(TwoClientPreferencesSyncTest,
   ASSERT_TRUE(ListPrefMatchChecker(prefs::kURLsToRestoreOnStartup).Wait());
 }
 
-IN_PROC_BROWSER_TEST_F(TwoClientPreferencesSyncTest,
-                       E2E_ENABLED(SingleClientEnabledEncryptionBothChanged)) {
+// Disabled due to flakiness on Chrome OS: https://crbug.com/873902.
+#if defined(OS_CHROMEOS)
+#define MAYBE_SingleClientEnabledEncryptionBothChanged \
+  DISABLED_SingleClientEnabledEncryptionBothChanged
+#else
+#define MAYBE_SingleClientEnabledEncryptionBothChanged \
+  SingleClientEnabledEncryptionBothChanged
+#endif
+IN_PROC_BROWSER_TEST_F(
+    TwoClientPreferencesSyncTest,
+    E2E_ENABLED(MAYBE_SingleClientEnabledEncryptionBothChanged)) {
   ASSERT_TRUE(SetupSync());
   ASSERT_TRUE(BooleanPrefMatchChecker(prefs::kHomePageIsNewTabPage).Wait());
   ASSERT_TRUE(StringPrefMatchChecker(prefs::kHomePage).Wait());