Update comment in aligned_memory.h to refer to unique_ptr

This is partially from upstream 093de9b30c0ba and partially from
https://codereview.chromium.org/1939833002/.

Change-Id: I480d9c21ead9375c407ae64bdf78c94779ecb072
Reviewed-on: https://chromium-review.googlesource.com/341661
Reviewed-by: Scott Graham <scottmg@chromium.org>
1 file changed