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

build/android/pylib/utils/device_temp_file.py

Index: build/android/pylib/utils/device_temp_file.py
diff --git a/build/android/pylib/utils/device_temp_file.py b/build/android/pylib/utils/device_temp_file.py
index 4623b9047bb37fc3b35fab4fc07dba834f509538..1364f7a7d93872fe757c2ca96e9ccb270781c1e3 100644
--- a/build/android/pylib/utils/device_temp_file.py
+++ b/build/android/pylib/utils/device_temp_file.py
@@ -6,6 +6,8 @@
 
 # pylint: disable=W0622
 
+import threading
+
 from pylib import cmd_helper
 from pylib.device import device_errors
 
@@ -43,11 +45,16 @@ class DeviceTempFile(object):
   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