Switch to use Win32 CONDITION_VARIABLE like Chromium.

This greatly simplifies the implementation of ConditionVariable
class for Windows with better performance.

Bug:NO

Change-Id: Iea5e5cb80520a966aeb687bebb4b5256396cb13b
Reviewed-on: https://chromium-review.googlesource.com/519542Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Commit-Queue: Loo Rong Jie <loorongjie@gmail.com>
Cr-Commit-Position: refs/heads/master@{#45651}