This fixes the counter inconsistencies and makes use of the already existing
mechanism for partially releasing memory.

This reverts commit c8e6cdfd.

Bug: chromium:724947
Change-Id: I2a7b52a28654fd2524df502a353997393d4f53ac
Reviewed-on: https://chromium-review.googlesource.com/530369Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45890}