The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3fd3d177ed8670ec79bcb54c7f66a3b80634b432

commit 3fd3d177ed8670ec79bcb54c7f66a3b80634b432
Author: Alexandr Ilin <alexilin@chromium.org>
Date: Wed Sep 12 17:54:14 2018

base: Report SharedMemory.CreateError histogram on Mac

The SharedMemory.CreateError histogram is useful for investigation of errors
related to the shared memory, but it has been being reported only on Windows.

This CL also adds the SharedMemory.CreateMacError with a return code of a
failed system call used for shared memory creation. It's similar to
SharedMemory.CreateWinError.

Bug: 881808
Change-Id: Ib53af312dfbd07ab86ecb8bd9c5577f00c0c0f14
Reviewed-on: https://chromium-review.googlesource.com/1213265
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Alexandr Ilin <alexilin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#590749}
[modify] https://crrev.com/3fd3d177ed8670ec79bcb54c7f66a3b80634b432/base/memory/platform_shared_memory_region.h
[modify] https://crrev.com/3fd3d177ed8670ec79bcb54c7f66a3b80634b432/base/memory/platform_shared_memory_region_mac.cc
[modify] https://crrev.com/3fd3d177ed8670ec79bcb54c7f66a3b80634b432/base/memory/platform_shared_memory_region_win.cc
[modify] https://crrev.com/3fd3d177ed8670ec79bcb54c7f66a3b80634b432/tools/metrics/histograms/enums.xml
[modify] https://crrev.com/3fd3d177ed8670ec79bcb54c7f66a3b80634b432/tools/metrics/histograms/histograms.xml