[BattOr] Add mac BattOr test for steady state cases.

tools/perf/benchmarks/battor.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.
 
 from core import perf_benchmark
 from telemetry.timeline import chrome_trace_category_filter
 from telemetry.web_perf import timeline_based_measurement
 import page_sets
 from telemetry import benchmark
 
@@ skipping 112 matching lines @@
 @benchmark.Enabled('mac')
 class BattOrTrivialPages(_BattOrBenchmark):
 
   def CreateStorySet(self, options):
     # We want it to wait for 30 seconds to be comparable to legacy power tests.
     return page_sets.MacGpuTrivialPagesStorySet(wait_in_seconds=30)
 
   @classmethod
   def Name(cls):
     return 'battor.trivial_pages'
+
+@benchmark.Enabled('mac')
+class BattOrSteadyStatePages(_BattOrBenchmark):
+
+  def CreateStorySet(self, options):
+    # We want it to wait for 30 seconds to be comparable to legacy power tests.
+    return page_sets.IdleAfterLoadingStories(wait_in_seconds=30)
+
+  @classmethod
+  def Name(cls):
+    return 'battor.steady_state'