[Sampling profiler] Move CONTEXT initialization into CopyStack()

Moves the initialization closer to the setting of the CONTEXT from the
register state, to facilitate future encapsulation and cross-platform
abstraction.

Bug: 909957
Change-Id: I375160269ebe87bd754faa4eb08a3b486d9df1e7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1529573
Commit-Queue: Mike Wittman <wittman@chromium.org>
Reviewed-by: Charlie Andrews <charliea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#643151}
1 file changed