Adding dumpsys based power monitor for android.

tools/telemetry/telemetry/core/platform/power_monitor/android_ds2784_power_monitor.py

Index: tools/telemetry/telemetry/core/platform/power_monitor/android_ds2784_power_monitor.py
diff --git a/tools/telemetry/telemetry/core/platform/power_monitor/android_ds2784_power_monitor.py b/tools/telemetry/telemetry/core/platform/power_monitor/android_ds2784_power_monitor.py
index 16474b762d50e11f6c853db9aec108a3f6ed0b6d..f96a4777ae680a1b69c92fe4c13994241adc7ee1 100644
--- a/tools/telemetry/telemetry/core/platform/power_monitor/android_ds2784_power_monitor.py
+++ b/tools/telemetry/telemetry/core/platform/power_monitor/android_ds2784_power_monitor.py
@@ -39,7 +39,7 @@ class DS2784PowerMonitor(power_monitor.PowerMonitor):
   def _HasFuelGauge(self):
     return self._adb.FileExistsOnDevice(CHARGE_COUNTER)
 
-  def CanMonitorPowerAsync(self):
+  def CanMonitorPower(self):
     if not self._HasFuelGauge():
       return False
     if self._IsDeviceCharging():
@@ -47,16 +47,16 @@ class DS2784PowerMonitor(power_monitor.PowerMonitor):
       return False
     return True
 
-  def StartMonitoringPowerAsync(self):
+  def StartMonitoringPower(self, browser):
     assert not self._powermonitor_process_port, (
-        'Must call StopMonitoringPowerAsync().')
+        'Must call StopMonitoringPower().')
     self._powermonitor_process_port = int(self._adb.RunShellCommand(
         '%s %d %s %s %s' % (self._file_poller_binary, SAMPLE_RATE_HZ,
             CHARGE_COUNTER, CURRENT, VOLTAGE))[0])
 
-  def StopMonitoringPowerAsync(self):
+  def StopMonitoringPower(self):
     assert self._powermonitor_process_port, (
-        'StartMonitoringPowerAsync() not called.')
+        'StartMonitoringPower() not called.')
     try:
       result = '\n'.join(self._adb.RunShellCommand(
           '%s %d' % (self._file_poller_binary,
@@ -71,7 +71,7 @@ class DS2784PowerMonitor(power_monitor.PowerMonitor):
     """Parse output of powermonitor command line utility.
 
     Returns:
-        Dictionary in the format returned by StopMonitoringPowerAsync().
+        Dictionary in the format returned by StopMonitoringPower().
     """
     power_samples = []
     total_energy_consumption_mwh = 0