[tools/perf] Disable tab_switching.typical_25 on Mac

Bug: 747026
Change-Id: If3154377583d9617516d6c2f4596d1da35272b97
Reviewed-on: https://chromium-review.googlesource.com/595352Reviewed-by: Ned Nguyen <nednguyen@google.com>
Reviewed-by: Juan Antonio Navarro Pérez <perezju@chromium.org>
Commit-Queue: Vovo Yang <vovoy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491325}

tools/perf/benchmarks/tab_switching.py

@@ -48,4 +48,6 @@ class TabSwitchingTypical25(perf_benchmark.PerfBenchmark):
       def SetExpectations(self):
         self.PermanentlyDisableBenchmark([story.expectations.ALL_MOBILE],
                                          'Desktop benchmark.')
+        self.DisableStory('multitab:misc:typical24',
+                          [story.expectations.ALL_MAC], 'crbug.com/747026')
     return StoryExpectations()