tools: Add tough_fast_scrolling_cases page set.

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.
 
 from benchmarks import silk_flags
 import page_sets
 from measurements import smoothness
 from telemetry import benchmark
 
 
@@ skipping 111 matching lines @@
 
 @benchmark.Enabled('android')
 class SmoothnessGpuRasterizationPolymer(benchmark.Benchmark):
   """Measures rendering statistics for the Polymer cases with GPU rasterization
   """
   tag = 'gpu_rasterization'
   test = smoothness.Smoothness
   page_set = page_sets.PolymerPageSet
   def CustomizeBrowserOptions(self, options):
     silk_flags.CustomizeBrowserOptionsForGpuRasterization(options)
+
+class SmoothnessToughFastScrollingCases(benchmark.Benchmark):
+  test = smoothness.Smoothness
+  page_set = page_sets.ToughScrollingCasesPageSet
+  options = {'page_label_filter' : 'fastscrolling'}