DevTools: fix bookkeeping when evicting POST data

Due to the bug, free space size was not updated when the POST data was
evicted, resulting in crash.

TBR=eostroukhov@chromium.org

(cherry picked from commit c9a324bf2fb731f1f9ef94dc4068cdc77140a5d6)

Bug: 813187
Change-Id: I8c4a3762eaa2ecf6ce58fccc639846c24cc9d6c8
Reviewed-on: https://chromium-review.googlesource.com/927643
Commit-Queue: Eugene Ostroukhov <eostroukhov@chromium.org>
Reviewed-by: Eugene Ostroukhov <eostroukhov@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#537977}
Reviewed-on: https://chromium-review.googlesource.com/932005
Cr-Commit-Position: refs/branch-heads/3325@{#550}
Cr-Branched-From: bc084a8b5afa3744a74927344e304c02ae54189f-refs/heads/master@{#530369}
3 files changed