The allocations vector does not need to be dynamically allocated, we can
just std::move it around instead.

Change-Id: If38af59deeccc06005397f255e18a2fa1bdf4298
Reviewed-on: https://chromium-review.googlesource.com/1099063
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53727}