Add key_idle_power_cases for ensuring idle activity on Android

tools/perf/benchmarks/thread_times.py

Index: tools/perf/benchmarks/thread_times.py
diff --git a/tools/perf/benchmarks/thread_times.py b/tools/perf/benchmarks/thread_times.py
index 9d7400f8d2d4b1d9d59960d900d9303cb9b7cf7c..ea0f6365f7747422c136f90d063b6512bb621a34 100644
--- a/tools/perf/benchmarks/thread_times.py
+++ b/tools/perf/benchmarks/thread_times.py
@@ -9,6 +9,10 @@ from measurements import thread_times
 import page_sets
 
 class _ThreadTimes(benchmark.Benchmark):
+  def __init__(self, measure_per_frame=True):
+    super(_ThreadTimes, self).__init__()
+    self._measure_per_frame = measure_per_frame
+
   @classmethod
   def AddBenchmarkCommandLineArgs(cls, parser):
     parser.add_option('--report-silk-details', action='store_true',
@@ -19,7 +23,8 @@ class _ThreadTimes(benchmark.Benchmark):
     return 'thread_times'
 
   def CreatePageTest(self, options):
-    return thread_times.ThreadTimes(options.report_silk_details)
+    return thread_times.ThreadTimes(options.report_silk_details,
+                                    self._measure_per_frame)
 
 
 @benchmark.Enabled('android')
@@ -89,3 +94,15 @@ class ThreadTimesPolymer(_ThreadTimes):
   def Name(cls):
     return 'thread_times.polymer'
 
+@benchmark.Enabled('android')
+class ThreadTimesKeyPowerCases(_ThreadTimes):
+  """Measures timeline metrics for sites that should be idle in foreground
+  and background scenarios. The metrics are aggregated rather than per-frame."""
+  page_set = page_sets.KeyPowerCasesPageSet
+
+  def __init__(self):
+    super(ThreadTimesKeyPowerCases, self).__init__(measure_per_frame=False)
+
+  @classmethod
+  def Name(cls):
+    return 'thread_times.key_power_cases'