The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/tools/build/+/def42bb00d63fd1eaa379e64949bc12adb49df51

commit def42bb00d63fd1eaa379e64949bc12adb49df51
Author: Andrew Grieve <agrieve@chromium.org>
Date: Thu Dec 13 01:35:02 2018

binary_size_trybot.py: Use a tempdir rather than output_dir for .size files

Using the output directory didn't work when changes add landmines.

Bug:  914613 
Change-Id: I6fbce8f65e661aeb634f0d33183a8706cdc2b7ee
Reviewed-on: https://chromium-review.googlesource.com/c/1375011
Auto-Submit: agrieve <agrieve@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>

[modify] https://crrev.com/def42bb00d63fd1eaa379e64949bc12adb49df51/scripts/slave/README.recipes.md
[modify] https://crrev.com/def42bb00d63fd1eaa379e64949bc12adb49df51/scripts/slave/recipes/binary_size_trybot.expected/unexpected_increase.json
[modify] https://crrev.com/def42bb00d63fd1eaa379e64949bc12adb49df51/scripts/slave/recipes/binary_size_trybot.expected/normal_build.json
[modify] https://crrev.com/def42bb00d63fd1eaa379e64949bc12adb49df51/scripts/slave/recipes/binary_size_trybot.expected/malformed_results_json.json
[modify] https://crrev.com/def42bb00d63fd1eaa379e64949bc12adb49df51/scripts/slave/recipes/binary_size_trybot.py

Verified bot seems okay.