Update usb charging command to wait for it to succeed.

build/android/pylib/android_commands.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Provides an interface to communicate with the device via the adb command.
 
 Assumes adb binary is currently on system path.
 """
 # pylint: disable-all
 
@@ skipping 1852 matching lines @@
     return None
 
   def CanControlUsbCharging(self):
     return self._GetControlUsbChargingCommand() is not None
 
   def DisableUsbCharging(self):
     command = self._GetControlUsbChargingCommand()
     if not command:
       raise Exception('Unable to act on usb charging.')
     disable_command = command['disable_command']
-    self.RunShellCommand(disable_command)
+    # Do not loop directly on self.IsDeviceCharging to cut the number of calls
+    # to the device.
+    while True:
+      self.RunShellCommand(disable_command)
+      if not self.IsDeviceCharging():
+        break
 
   def EnableUsbCharging(self):
     command = self._GetControlUsbChargingCommand()
     if not command:
       raise Exception('Unable to act on usb charging.')
     disable_command = command['enable_command']
-    self.RunShellCommand(disable_command)
+    # Do not loop directly on self.IsDeviceCharging to cut the number of calls
+    # to the device.
+    while True:
+      self.RunShellCommand(disable_command)
+      if self.IsDeviceCharging():
+        break
+
+  def IsDeviceCharging(self):
+    for line in self.RunShellCommand('dumpsys battery'):
+      if 'powered: ' in line:
+        if line.split('powered: ')[1] == 'true':
+          return True
 
 
 class NewLineNormalizer(object):
   """A file-like object to normalize EOLs to '\n'.
 
   Pexpect runs adb within a pseudo-tty device (see
   http://www.noah.org/wiki/pexpect), so any '\n' printed by adb is written
   as '\r\n' to the logfile. Since adb already uses '\r\n' to terminate
   lines, the log ends up having '\r\r\n' at the end of each line. This
   filter replaces the above with a single '\n' in the data stream.
   """
   def __init__(self, output):
     self._output = output
 
   def write(self, data):
     data = data.replace('\r\r\n', '\n')
     self._output.write(data)
 
   def flush(self):
     self._output.flush()