Disable InstantExtendedTest.NavigateBackToNTP, since it's extremely flaky.

chrome/browser/ui/search/instant_extended_interactive_uitest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <sstream>
 
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_base.h"
 #include "base/metrics/histogram_samples.h"
@@ skipping 1564 matching lines @@
   active_tab->GetController().GoForward();
   load_stop_observer_2.Wait();
 
   // Commit the search by pressing 'Enter'.
   FocusOmnibox();
   EXPECT_EQ(ASCIIToUTF16("cattles"), omnibox()->GetText());
   PressEnterAndWaitForNavigation();
   EXPECT_EQ(ASCIIToUTF16("cattles"), omnibox()->GetText());
 }
 
-// Flaky on Mac Tests bot.
-#if defined(OS_MACOSX)
-#define MAYBE_NavigateBackToNTP DISABLED_NavigateBackToNTP
-#else
-#define MAYBE_NavigateBackToNTP NavigateBackToNTP
-#endif
-IN_PROC_BROWSER_TEST_F(InstantExtendedTest, MAYBE_NavigateBackToNTP) {
+// Flaky on all bots since re-enabled in r208032, crbug.com/253092
+IN_PROC_BROWSER_TEST_F(InstantExtendedTest, DISABLED_NavigateBackToNTP) {
   ASSERT_NO_FATAL_FAILURE(SetupInstant(browser()));
   FocusOmniboxAndWaitForInstantNTPSupport();
 
   // Open a new tab page.
   ui_test_utils::NavigateToURLWithDisposition(
       browser(),
       GURL(chrome::kChromeUINewTabURL),
       NEW_FOREGROUND_TAB,
       ui_test_utils::BROWSER_TEST_WAIT_FOR_TAB);
   EXPECT_EQ(2, browser()->tab_strip_model()->count());
@@ skipping 35 matching lines @@
   content::WindowedNotificationObserver load_stop_observer_2(
       content::NOTIFICATION_LOAD_STOP,
       content::Source<content::NavigationController>(
           &active_tab->GetController()));
   active_tab->GetController().GoBack();
   load_stop_observer_2.Wait();
 
   active_tab = browser()->tab_strip_model()->GetActiveWebContents();
   EXPECT_TRUE(chrome::IsInstantNTP(active_tab));
 }