Wire sync shutdown reason from PSS all the way down to sync manager.

Wire sync shutdown reason from PSS all the way down to sync manager.
This is to prepare for on-demand backup where backup manger needs to persist
backup data if the shutdown is due to switching to syncing. No behavior changes are introduced by this cl.

BUG=362679
NOTRY=true

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=287799

[Nicolas Zea, 2014-08-01 00:34:58]

lgtm

[haitaol1, 2014-08-05 02:08:48]

The CQ bit was checked by haitaol@chromium.org

[commit-bot: I haz the power, 2014-08-05 02:11:25]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/haitaol@chromium.org/437683002/1

[commit-bot: I haz the power, 2014-08-05 02:18:48]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  chromium_presubmit on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)
  linux_chromium_chromeos_rel_swarming on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  ios_rel_device_ninja on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device_ni...)
  win8_chromium_rel on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win8_chromium_rel...)
  win_chromium_x64_rel on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[commit-bot: I haz the power, 2014-08-05 02:21:40]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-08-05 02:21:41]

Try jobs failed on following builders:
  linux_chromium_chromeos_rel_swarming on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  ios_rel_device_ninja on tryserver.chromium.mac
(http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device_ni...)
  win8_chromium_rel on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win8_chromium_rel...)

[haitaol1, 2014-08-06 00:05:22]

The CQ bit was checked by haitaol@chromium.org

[commit-bot: I haz the power, 2014-08-06 00:06:18]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/haitaol@chromium.org/437683002/20001

[commit-bot: I haz the power, 2014-08-06 06:35:11]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu/builds/43048)

[commit-bot: I haz the power, 2014-08-06 07:35:22]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-08-06 07:35:23]

Try jobs failed on following builders:
  win_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/win_gpu_triggered...)

[haitaol1, 2014-08-06 17:30:51]

The CQ bit was checked by haitaol@chromium.org

[commit-bot: I haz the power, 2014-08-06 17:32:02]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/haitaol@chromium.org/437683002/40001

[commit-bot: I haz the power, 2014-08-06 17:34:32]

Change committed as 287799