GitLab

This CL contains:
 - Moves WTF::GetPtr overload for RefPtr to wtf/GetPtr.h,
 - Moves RefPtrValuePeeker to wtf/HashFunctions.h
 - Merges WTF::AdoptRef and base::AdoptRef.
as a preparation of RefPtr.h removal.

Bug: 763844
Change-Id: Iac2cfe6af0304ed4ea180f6ed50a08e9065672b9
Reviewed-on: https://chromium-review.googlesource.com/727683Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510145}