[Telemetry] Add test case for power usage of background animations/heavy tab.

tools/perf/benchmarks/tab_switching.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 telemetry import test
 
 from measurements import tab_switching
 
 
 class TabSwitchingTop10(test.Test):
   test = tab_switching.TabSwitching
   page_set = 'page_sets/top_10.py'
 
 class TabSwitchingFiveBlankTabs(test.Test):
   test = tab_switching.TabSwitching
   page_set = 'page_sets/five_blank_pages.json'
   options = {'pageset_repeat': 10}
+
+class TabSwitchingToughEnergyCases(test.Test):
+  test = tab_switching.TabSwitching
+  page_set = 'page_sets/tough_energy_cases.json'
+  options = {'pageset_repeat': 10}