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In theory this will reduce memory wasted by std::deque. It may also help diagnose
some puzzling crashes we've seen related to the immediate incomming and work queues.

BUG=674625, 674895
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2579773002
Cr-Commit-Position: refs/heads/master@{#443450}