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 1cdbe93101db986fb44930305162c66e89c44fe7..812cbca70b5fed38ae121b9559081832a7803103 100644
--- a/tools/perf/benchmarks/thread_times.py
+++ b/tools/perf/benchmarks/thread_times.py
@@ -94,3 +94,17 @@ class ThreadTimesPolymer(_ThreadTimes):
   def Name(cls):
     return 'thread_times.polymer'
 
+@benchmark.Enabled('android')
+class ThreadTimesKeyIdlePowerCases(_ThreadTimes):
+  """Measures timeline metrics for sites that should be idle in foreground
+  and background scenarios. The metrics are per-second rather than per-frame."""
+  page_set = page_sets.KeyIdlePowerCasesPageSet
+
+  @classmethod
+  def Name(cls):
+    return 'thread_times.key_idle_power_cases'
+
+  @classmethod
+  def ValueCanBeAddedPredicate(cls, value, _):
+    # Only report per-second metrics.
+    return 'per_frame' not in value.name and 'mean_frame' not in value.name