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

chrome/browser/ui/search/instant_extended_interactive_uitest.cc

Index: chrome/browser/ui/search/instant_extended_interactive_uitest.cc
diff --git a/chrome/browser/ui/search/instant_extended_interactive_uitest.cc b/chrome/browser/ui/search/instant_extended_interactive_uitest.cc
index 75a919a6e635e9b165da2fb0f94cf21ed1a937a4..fcc87fae960a61e24ff33eff776e3db4573cd63e 100644
--- a/chrome/browser/ui/search/instant_extended_interactive_uitest.cc
+++ b/chrome/browser/ui/search/instant_extended_interactive_uitest.cc
@@ -1582,13 +1582,8 @@ IN_PROC_BROWSER_TEST_F(InstantExtendedTest,
   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();