Introduce call_stack_profile_encoding.{cc,h}

This is to remove duplicated code in call_stack_profile_builder.cc and
call_stack_profile_collector.cc.

Bug: 851163
Change-Id: I304aa107f84f1d4072f3a3eb5dd0e58aed52a30b
Reviewed-on: https://chromium-review.googlesource.com/1176197
Reviewed-by: Mike Wittman <wittman@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Xi Cheng <chengx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583478}
5 files changed