[heap profiler] Merge Client and ProfilerWrapper classes

... into ProfilingClient.

BUG=923459
TBR=sky@chromium.org

Change-Id: I66ef41790f7878318848022100871f61462058d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1582334
Commit-Queue: Alexei Filippov <alph@chromium.org>
Reviewed-by: Sergey Volk <servolk@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654247}
12 files changed