Disable flaky tests on Mac.

chrome/browser/sessions/better_session_restore_browsertest.cc

 // Copyright (c) 2012 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 <stddef.h>
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
@@ skipping 442 matching lines @@
 }
 
 IN_PROC_BROWSER_TEST_F(ContinueWhereILeftOffTest, PRE_CookiesClearedOnExit) {
   // Normally cookies are restored.
   CheckReloadedPageRestored();
   // ... but not if the content setting is set to clear on exit.
   CookieSettingsFactory::GetForProfile(browser()->profile())
       ->SetDefaultCookieSetting(CONTENT_SETTING_SESSION_ONLY);
 }
 
+// Flaky on Mac. http://crbug.com/656211.
+#if defined(OS_MACOSX)
+#define MAYBE_CookiesClearedOnExit DISABLED_CookiesClearedOnExit
+#else
+#define MAYBE_CookiesClearedOnExit CookiesClearedOnExit
+#endif
 IN_PROC_BROWSER_TEST_F(ContinueWhereILeftOffTest, CookiesClearedOnExit) {
   CheckReloadedPageNotRestored();
 }
 
 IN_PROC_BROWSER_TEST_F(ContinueWhereILeftOffTest, PRE_Post) {
   PostFormWithPage("post.html", false);
 }
 
 IN_PROC_BROWSER_TEST_F(ContinueWhereILeftOffTest, Post) {
   CheckFormRestored(true, false);
@@ skipping 415 matching lines @@
   CookieSettingsFactory::GetForProfile(new_browser->profile())
       ->SetDefaultCookieSetting(CONTENT_SETTING_SESSION_ONLY);
   // ... even if background mode is active.
   EnableBackgroundMode();
   new_browser = QuitBrowserAndRestore(new_browser, true);
   StoreDataWithPage(new_browser, "cookies.html");
   DisableBackgroundMode();
   new_browser = QuitBrowserAndRestore(new_browser, true);
   StoreDataWithPage(new_browser, "cookies.html");
 }