Disable test on Mac due to flaky timeouts.

chrome/browser/sessions/session_restore_browsertest.cc

Index: chrome/browser/sessions/session_restore_browsertest.cc
diff --git a/chrome/browser/sessions/session_restore_browsertest.cc b/chrome/browser/sessions/session_restore_browsertest.cc
index efd6e379bacbf4532b744e2fb47a18d54e4cfe69..8daee1190647c3874e2d7ccc4444ccad715357f7 100644
--- a/chrome/browser/sessions/session_restore_browsertest.cc
+++ b/chrome/browser/sessions/session_restore_browsertest.cc
@@ -1465,8 +1465,9 @@ IN_PROC_BROWSER_TEST_F(SmartSessionRestoreTest, PRE_CorrectLoadingOrder) {
   new_browser->tab_strip_model()->ActivateTabAt(1, true);
 }
 
-// PRE_CorrectLoadingOrder is flaky on ChromeOS MSAN. https://crbug.com/582323.
-#if defined (OS_CHROMEOS) && defined(MEMORY_SANITIZER)
+// PRE_CorrectLoadingOrder is flaky on ChromeOS MSAN: https://crbug.com/582323
+// And Mac: https://crbug.com/656687
+#if (defined(OS_CHROMEOS) && defined(MEMORY_SANITIZER)) || defined(OS_MACOSX)
 #define MAYBE_CorrectLoadingOrder DISABLED_CorrectLoadingOrder
 #else
 #define MAYBE_CorrectLoadingOrder CorrectLoadingOrder