I compared build time of chrome on some platforms without goma backend cache case.

* 4C/8T MacBook Pro
x20: 1900s
x40: 1357s

* 24C/48T Z840 Windows 10:
x20: 747s
x40: 733s

* 24C/48T Z840 Linux:
x20: 267s
x40: 189s

Change-Id: Iaa4c1e770ffcbc3f7d355060d0df03bf3f3b344f
Reviewed-on: https://chromium-review.googlesource.com/c/1457037
Auto-Submit: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Shinya Kawanaka <shinyak@chromium.org>
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>