The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aac97fe5f3cb5890bedac2a2ba9fec6b3e8c16fc

commit aac97fe5f3cb5890bedac2a2ba9fec6b3e8c16fc
Author: Ben Chan <benchan@chromium.org>
Date: Tue Nov 07 01:15:59 2017

Chrome OS: Fix multi-part SMS handling in SMSClient.

SMSClient incorrectly assumes that a SMS is fully received upon
receiving an "Added" signal emitted from the
org.freedesktop.ModemManager1.Modem.Messaging interface by ModemManager.
For a multi-part SMS, the Added signal is emitted by ModemManager upon
receiving the first part and no further Added signal is emitted on
subsequent parts. As the SMS content isn't available in the first SMS
part, it results in no notification shown. This CL fixes SMSClient to
monitor the "State" property of the SMS object exposed by ModemManager
to determine when the SMS is fully received.

Bug:  781042 
Test: Verify that UI pops up a notification upon receiving a multi-part SMS.
Change-Id: Ide06e5cfafa3127c44a5df653ad701e05473615f
Reviewed-on: https://chromium-review.googlesource.com/754335
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Ben Chan <benchan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#514329}
[modify] https://crrev.com/aac97fe5f3cb5890bedac2a2ba9fec6b3e8c16fc/chromeos/dbus/sms_client.cc
[modify] https://crrev.com/aac97fe5f3cb5890bedac2a2ba9fec6b3e8c16fc/chromeos/dbus/sms_client.h
[modify] https://crrev.com/aac97fe5f3cb5890bedac2a2ba9fec6b3e8c16fc/chromeos/network/network_sms_handler.cc