Adding dumpsys based power monitor for android.

tools/perf/metrics/power.py

Index: tools/perf/metrics/power.py
diff --git a/tools/perf/metrics/power.py b/tools/perf/metrics/power.py
index 1196dbf22171724550728c9260701e7ee3dcdc8d..76c55cebe6963a30a3f18d1c39afe61611f7a0f1 100644
--- a/tools/perf/metrics/power.py
+++ b/tools/perf/metrics/power.py
@@ -34,8 +34,8 @@ class PowerMetric(Metric):
     if not self._running:
       return
     self._running = False
-    self._results = self._browser.platform.StopMonitoringPowerAsync()
-    if self._results: # StopMonitoringPowerAsync() can return None.
+    self._results = self._browser.platform.StopMonitoringPower()
+    if self._results: # StopMonitoringPower() can return None.
       self._results['cpu_stats'] = (
           _SubtractCpuStats(self._browser.cpu_stats, self._starting_cpu_stats))
 
@@ -45,7 +45,7 @@ class PowerMetric(Metric):
 
     # Friendly informational messages if measurement won't run.
     system_supports_power_monitoring = (
-        factory.GetPlatformBackendForCurrentOS().CanMonitorPowerAsync())
+        factory.GetPlatformBackendForCurrentOS().CanMonitorPower())
     if system_supports_power_monitoring:
       if not PowerMetric.enabled:
         logging.warning(
@@ -58,7 +58,7 @@ class PowerMetric(Metric):
     if not PowerMetric.enabled:
       return
 
-    if not tab.browser.platform.CanMonitorPowerAsync():
+    if not tab.browser.platform.CanMonitorPower():
       return
 
     self._results = None
@@ -67,14 +67,14 @@ class PowerMetric(Metric):
 
     # This line invokes top a few times, call before starting power measurement.
     self._starting_cpu_stats = self._browser.cpu_stats
-    self._browser.platform.StartMonitoringPowerAsync()
+    self._browser.platform.StartMonitoringPower(self._browser)
     self._running = True
 
   def Stop(self, _, tab):
     if not PowerMetric.enabled:
       return
 
-    if not tab.browser.platform.CanMonitorPowerAsync():
+    if not tab.browser.platform.CanMonitorPower():
       return
 
     self._StopInternal()
@@ -110,6 +110,10 @@ def _SubtractCpuStats(cpu_stats, start_cpu_stats):
     # Skip any process_types that are empty.
     if (not cpu_stats[process_type]) or (not start_cpu_stats[process_type]):
       continue
+    # Skip if IdleWakeupCount is not present.
+    if (('IdleWakeupCount' not in cpu_stats[process_type]) or
+        ('IdleWakeupCount' not in start_cpu_stats[process_type])):
+      continue
     idle_wakeup_delta = (cpu_stats[process_type]['IdleWakeupCount'] -
                         start_cpu_stats[process_type]['IdleWakeupCount'])
     cpu_delta[process_type] = idle_wakeup_delta