[Telemetry] Support dumpsys power monitoring on the Nexus 5.

This adds the necessary commands to programmatically disable charging
on the Nexus 5 as well as fixing a bug in the dumpsys power monitor.

BUG=314481

Review URL: https://codereview.chromium.org/617453004

Cr-Commit-Position: refs/heads/master@{#297428}

build/android/pylib/android_commands.py

@@ -78,6 +78,20 @@ CONTROL_USB_CHARGING_COMMANDS = [
     'disable_command':
         'echo 1 > /sys/module/pm8921_charger/parameters/disabled',
   },
+  {
+    # Nexus 5
+    # Setting the HIZ bit of the bq24192 causes the charger to actually ignore
+    # energy coming from USB. Setting the power_supply offline just updates the
+    # Android system to reflect that.
+    'witness_file': '/sys/kernel/debug/bq24192/INPUT_SRC_CONT',
+    'enable_command': (
+        'echo 0x4A > /sys/kernel/debug/bq24192/INPUT_SRC_CONT && '
+        'echo 1 > /sys/class/power_supply/usb/online'),
+    'disable_command': (
+        'echo 0xCA > /sys/kernel/debug/bq24192/INPUT_SRC_CONT && '
+        'chmod 644 /sys/class/power_supply/usb/online && '
+        'echo 0 > /sys/class/power_supply/usb/online'),
+  },
 ]
 
 class DeviceTempFile(object):

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

@@ -45,7 +45,8 @@ class DumpsysPowerMonitor(sysfs_power_monitor.SysfsPowerMonitor):
     result = self._platform.RunCommand('dumpsys batterystats -c %s' % package)
     assert result, 'Dumpsys produced no output'
     return super(DumpsysPowerMonitor, self).CombineResults(
-        cpu_stats, DumpsysPowerMonitor.ParseSamplingOutput(package, result))
+        cpu_stats, DumpsysPowerMonitor.ParseSamplingOutput(package,
+                                                           result.split('\n')))
 
   @staticmethod
   def ParseSamplingOutput(package, dumpsys_output):
@@ -103,8 +104,9 @@ class DumpsysPowerMonitor(sysfs_power_monitor.SysfsPowerMonitor):
 
     # Find the uid of for the given package.
     if not package in uid_entries:
-      logging.warning('Unable to parse dumpsys output. ' +
-                      'Please upgrade the OS version of the device.')
+      logging.warning('Unable to parse dumpsys output. '
+                      'Please upgrade the OS version of the device.'
+                      'package=%s, uid_entries=%s' % (package, uid_entries))
       out_dict['energy_consumption_mwh'] = 0
       return out_dict
     uid = uid_entries[package]