tcmalloc: fix bookkeeping of span free objects

After fetching objects from a span, reset the previous field of the first
remaining object in the span.
Debug builds perform extra sanity checks on the state of the tcmalloc
metadata, which is causing them to fail without this fix.

BUG=724399,b:70905156

Change-Id: I33ad3097d13756d36032edde538ee87b09a1a4ee
Reviewed-on: https://chromium-review.googlesource.com/1195092
Reviewed-by: Will Harris <wfh@chromium.org>
Commit-Queue: Gabriel Marin <gmx@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#588193}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 5ca6a22ad7025a30cf670d6828ea6b33b3d0e418
1 file changed
tree: 7147790d445b0b80a96df492592534caa890b16e
  1. src/