As part of this, we could also look at adding tracing information to test execution: https://bugs.chromium.org/p/chromium/issues/detail?id=568352

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7ff10a8c4f7295430af4d3bac32ffb713fb42761

commit 7ff10a8c4f7295430af4d3bac32ffb713fb42761
Author: shenghuazhang <shenghuazhang@chromium.org>
Date: Tue Apr 11 04:12:11 2017

[Instrumentation Test Speed] Install apks in parallel with concurrent_adb enabled

The current install_apk installs all apks one by one. This CL enables
apks installation in parallel when execute the test with
command '--enable-concurrent-adb'. In this way, the total
individial_device_set_up time decreases.

BUG=670302

Review-Url: https://codereview.chromium.org/2791613003
Cr-Commit-Position: refs/heads/master@{#463529}

[modify] https://crrev.com/7ff10a8c4f7295430af4d3bac32ffb713fb42761/build/android/pylib/local/device/local_device_instrumentation_test_run.py