Reland: Optimization: Make clean-up of DeviceTempFile() async

build/android/pylib/utils/device_temp_file.py

 # Copyright 2013 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.
 
 """A temp file that automatically gets pushed and deleted from a device."""
 
 # pylint: disable=W0622
 
+import threading
+
 from pylib import cmd_helper
 from pylib.device import device_errors
 
 _COMMAND_TEMPLATE = (
     # Make sure that the temp dir is writable
     'test -d {dir} && '
     # If 5 random attempts fail, something is up.
     'for i in 1 2 3 4 5; do '
     'fn={dir}/{prefix}-$(date +%s)-"$RANDOM"{suffix};'
     'test -e "$fn" || break;'
@@ skipping 17 matching lines @@
     command = _COMMAND_TEMPLATE.format(
         dir=cmd_helper.SingleQuote(dir),
         suffix=cmd_helper.SingleQuote(suffix),
         prefix=cmd_helper.SingleQuote(prefix))
     self.name = self._adb.Shell(command)
     self.name_quoted = cmd_helper.SingleQuote(self.name)
 
   def close(self):
     """Deletes the temporary file from the device."""
     # ignore exception if the file is already gone.
-    try:
-      self._adb.Shell('rm -f %s' % self.name_quoted)
-    except device_errors.AdbCommandFailedError:
-      # file does not exist on Android version without 'rm -f' support (ICS)
-      pass
+    def helper():
+      try:
+        self._adb.Shell('rm -f %s' % self.name_quoted, expect_status=None)
+      except device_errors.AdbCommandFailedError:
+        # file does not exist on Android version without 'rm -f' support (ICS)
+        pass
+
+    # It shouldn't matter when the temp file gets deleted, so do so
+    # asynchronously.
+    threading.Thread(target=helper).start()
 
   def __enter__(self):
     return self
 
   def __exit__(self, type, value, traceback):
     self.close()