[tools/perf] Remove dead code in system_health_smoke_test.py

tools/perf/benchmarks/system_health_smoke_test.py

 # Copyright 2016 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.
 
 """Run all system health stories used by system health benchmarks.
 
 Only memory benchmarks are used when running these stories to make the total
 cycle time manageable. Other system health benchmarks should be using the same
 stories as memory ones, only with fewer actions (no memory dumping).
 """
 
 import unittest
 
 from core import perf_benchmark
 
 from telemetry import benchmark as benchmark_module
 from telemetry import decorators
 from telemetry.core import discover
 from telemetry.internal.browser import browser_finder
 from telemetry.testing import options_for_unittests
 from telemetry.testing import progress_reporter
 
 from benchmarks import system_health
 
 
-# We only cover memory system health
-_SH_BENCHMARKS_TO_SMOKE_TEST = [
-  system_health.DesktopMemorySystemHealth,
-  system_health.MobileMemorySystemHealth,
-]
-
-
 def GetSystemHealthBenchmarksToSmokeTest():
   sh_benchmark_classes = discover.DiscoverClassesInModule(
       system_health, perf_benchmark.PerfBenchmark,
       index_by_class_name=True).values()
   return list(b for b in sh_benchmark_classes if
               b.Name().startswith('system_health.memory'))
 
 
 _DISABLED_TESTS = frozenset({
   # crbug.com/624474
@@ skipping 90 matching lines @@
     # parsed during test time which happens after load_tests are called.
     # Since none of our system health benchmarks creates stories based on
     # command line options, it should be ok to pass options=None to
     # CreateStorySet.
     for story_to_smoke_test in (
         benchmark_class().CreateStorySet(options=None).stories):
       suite.addTest(
           _GenerateSmokeTestCase(benchmark_class, story_to_smoke_test))
 
   return suite