Rename ScopedTaskEnvironment::ExecutionMode

ScopedTaskEnvironment::ExecutionMode is becoming
ScopedTaskEnvironment::ThreadPoolExecutionMode

This CL was uploaded by git cl split.

R=qinmin@chromium.org

Bug: 708584
Change-Id: I83e15199cc8f11e4d46ba56b1ea7a15907e5c29e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1583753
Auto-Submit: Carlos Caballero <carlscab@google.com>
Reviewed-by: Min Qin <qinmin@chromium.org>
Commit-Queue: Min Qin <qinmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654023}
2 files changed