Update from https://crrev.com/328418

build/android/pylib/device/adb_wrapper.py

Index: build/android/pylib/device/adb_wrapper.py
diff --git a/build/android/pylib/device/adb_wrapper.py b/build/android/pylib/device/adb_wrapper.py
index 20787c19dc7b665d3140f3af4867da8d0d39f9b5..8e8abf8b5e01bcc7d9bdbc911b3f4e7a634e2758 100644
--- a/build/android/pylib/device/adb_wrapper.py
+++ b/build/android/pylib/device/adb_wrapper.py
@@ -450,7 +450,7 @@ class AdbWrapper(object):
       timeout: (optional) Timeout per try in seconds.
       retries: (optional) Number of retries to attempt.
     """
-    cmd = ['backup', path]
+    cmd = ['backup', '-f', path]
     if apk:
       cmd.append('-apk')
     if shared:
@@ -542,6 +542,24 @@ class AdbWrapper(object):
       raise device_errors.AdbCommandFailedError(
           ['root'], output, device_serial=self._device_serial)
 
+  def Emu(self, cmd, timeout=_DEFAULT_TIMEOUT,
+               retries=_DEFAULT_RETRIES):
+    """Runs an emulator console command.
+
+    See http://developer.android.com/tools/devices/emulator.html#console
+
+    Args:
+      cmd: The command to run on the emulator console.
+      timeout: (optional) Timeout per try in seconds.
+      retries: (optional) Number of retries to attempt.
+
+    Returns:
+      The output of the emulator console command.
+    """
+    if isinstance(cmd, basestring):
+      cmd = [cmd]
+    return self._RunDeviceAdbCmd(['emu'] + cmd, timeout, retries)
+
   @property
   def is_emulator(self):
     return _EMULATOR_RE.match(self._device_serial)