Disable some tests on Nexus 5X reference again

tools/perf/benchmarks/smoothness.py

 # 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.
 import multiprocessing
 
 from core import perf_benchmark
 
 from benchmarks import silk_flags
 from measurements import smoothness
 import page_sets
@@ skipping 480 matching lines @@
     return cls.IsSvelte(possible_browser)  # http://crbug.com/555089
 
 
 # http://crbug.com/522619 (mac/win)
 @benchmark.Disabled('win', 'mac')
 class SmoothnessScrollingToughAdCases(_Smoothness):
   """Measures rendering statistics while scrolling advertisements."""
   page_set = page_sets.ScrollingToughAdCasesPageSet
 
   @classmethod
+  def ShouldDisable(cls, possible_browser):  # http://crbug.com/597656
+    return (possible_browser.browser_type == 'reference' and
+            possible_browser.platform.GetDeviceTypeName() == 'Nexus 5X')
+
+  @classmethod
   def Name(cls):
     return 'smoothness.scrolling_tough_ad_cases'
 
 
 @benchmark.Disabled('android-reference')  # crbug.com/588786
 @benchmark.Disabled('mac', 'win')  # crbug.com/522619 (mac/win)
 class SmoothnessBidirectionallyScrollingToughAdCases(_Smoothness):
   """Measures rendering statistics while scrolling advertisements."""
   page_set = page_sets.BidirectionallyScrollingToughAdCasesPageSet
 
@@ skipping 10 matching lines @@
   """Measures rendering statistics while scrolling advertisements."""
   page_set = page_sets.SyntheticToughWebglAdCasesPageSet
 
   @classmethod
   def Name(cls):
     return 'smoothness.tough_webgl_ad_cases'
 
   @classmethod
   def ShouldDisable(cls, possible_browser):
     return cls.IsSvelte(possible_browser)  # http://crbug.com/574485