M55: Fix CrOS reverting to Save as PDF and random PDF preview fail

M55: Fix CrOS reverting to Save as PDF and random PDF preview fail

Increasing number of saved destinations caused a bug on Chrome OS -
destination always reverted to Save as PDF.

Also caused random "PDF failed to load" preview errors. This occurred
since the destinations were modified one after the other too quickly,
which caused a race condition that crashed PDF preview. This error
occurred ~1 in 10 times.

BUG=665455, 666426, 666595
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2516523002
Cr-Commit-Position: refs/heads/master@{#433408}
(cherry picked from commit b12aba73d3525867511b315a45d2dbc65acd2647)

Committed: https://chromium.googlesource.com/chromium/src/+/03dfb68a8d7f607a19a3a5f53319c02b899f7d3f

[Lei Zhang, 2016-11-22 10:09:17]

Description was changed from

==========
M55: Fix CrOS reverting to Save as PDF and random PDF preview fail

Increasing number of saved destinations caused a bug on Chrome OS -
destination always reverted to Save as PDF.

Also caused random "PDF failed to load" preview errors. This occurred
since the destinations were modified one after the other too quickly,
which caused a race condition that crashed PDF preview. This error
occurred ~1 in 10 times.

BUG=665455,666426,666595
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2516523002
Cr-Commit-Position: refs/heads/master@{#433408}
(cherry picked from commit b12aba73d3525867511b315a45d2dbc65acd2647)
==========

to

==========
M55: Fix CrOS reverting to Save as PDF and random PDF preview fail

Increasing number of saved destinations caused a bug on Chrome OS -
destination always reverted to Save as PDF.

Also caused random "PDF failed to load" preview errors. This occurred
since the destinations were modified one after the other too quickly,
which caused a race condition that crashed PDF preview. This error
occurred ~1 in 10 times.

BUG=665455,666426,666595
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2516523002
Cr-Commit-Position: refs/heads/master@{#433408}
(cherry picked from commit b12aba73d3525867511b315a45d2dbc65acd2647)

Committed:
https://chromium.googlesource.com/chromium/src/+/03dfb68a8d7f607a19a3a5f53319...
==========

[Lei Zhang, 2016-11-22 10:09:19]

Committed patchset #1 (id:1) manually as
03dfb68a8d7f607a19a3a5f53319c02b899f7d3f.