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

tools/android/loading/common_util.py

Index: tools/android/loading/common_util.py
diff --git a/tools/android/loading/common_util.py b/tools/android/loading/common_util.py
index 899062cb29f7f38e4f1b6ea57fa789c7ae754efd..3b52a21f1fb21639d136263e69fa0ebb08838ed4 100644
--- a/tools/android/loading/common_util.py
+++ b/tools/android/loading/common_util.py
@@ -148,3 +148,11 @@ def TimeoutScope(seconds, error_name):
     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))