Fix crash when syncing files on Drive.

Fix crash when syncing files on Drive.

A recent CL caused a crash due to undefined order of evaluating arguments in
C++. An invalid pointer was causing a crash on G++ builds only.

TEST=Tested manually on a Chromebook.
BUG=462999
Committed: https://crrev.com/120c67c5b4f8f87a3dbbf58043fc36532568bc70
Cr-Commit-Position: refs/heads/master@{#318857}

[mtomasz, 2015-03-03 08:29:27]

mtomasz@chromium.org changed reviewers:
+ hashimoto@chromium.org

[mtomasz, 2015-03-03 08:29:27]

@hashimoto: PTAL. Thanks.

[hashimoto, 2015-03-03 08:42:07]

lgtm

[mtomasz, 2015-03-03 08:42:49]

The CQ bit was checked by mtomasz@chromium.org

[commit-bot: I haz the power, 2015-03-03 08:43:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/977493002/1

[commit-bot: I haz the power, 2015-03-03 09:30:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-03 09:31:41]

Patchset 1 (id:??) landed as
https://crrev.com/120c67c5b4f8f87a3dbbf58043fc36532568bc70
Cr-Commit-Position: refs/heads/master@{#318857}