sandwich: Use cachetool's batch mode to speed-up cache processing.

tools/android/loading/common_util.py

 # Copyright (c) 2016 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.
 
 import contextlib
 import json
 import logging
 import os
 import re
 import shutil
@@ skipping 130 matching lines @@
     signal.signal(signal.SIGALRM, _signal_callback)
     if signal.alarm(seconds) != 0:
       raise TimeoutCollisionError(
           'Discarding an alarm that was scheduled before.')
     yield
   finally:
     signal.alarm(0)
     if signal.getsignal(signal.SIGALRM) != _signal_callback:
       raise TimeoutCollisionError('Looks like there is a signal.signal(signal.'
           'SIGALRM) made within the with statement.')
+
+
+@contextlib.contextmanager
+def TimeMeasurement(measurement_name):

[mattcary, 2016/07/01 12:09:29]

If this isn't used in this patch, make a separate CL for it. Then, eg, if the
online cache CL is rolled back you won't accidentally break anything that has
started to use TimeMeasurement.

[gabadie, 2016/07/01 14:10:26]

Done.

+  start = time.time()
+  yield
+  end = time.time()
+  logging.info('%s: %ds', measurement_name, (end - start))