Reland "Clean up out-of-process heap_profiling support"

This is a reland of cc5b68bf01f60392587804e02919f9bd9d7c6a83

Reland fixes linkage of Fuchsia cast build. The original CL broke
it by moving the CastContentUtilityClient constructor out-of-line
into cast_content_utility_client.cc, which was not being linked into
Fuchsia builds. Now that it no longer depends on the heap_profiling
service, it's fine to build everywhere.

Original change's description:
> Clean up out-of-process heap_profiling support
>
> The heap_profiling service is now only run in-process, so this removes a
> bunch of dead utility process code supporting its use out-of-process.
>
> Bug: None
> Change-Id: If4836adfbb6c551d239927972013a74ef7822b38
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1621346
> Commit-Queue: Ken Rockot <rockot@google.com>
> Reviewed-by: Luke Halliwell <halliwell@chromium.org>
> Reviewed-by: Bo <boliu@chromium.org>
> Reviewed-by: Scott Violet <sky@chromium.org>
> Reviewed-by: Daniel Cheng <dcheng@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#663191}

TBR=boliu@chromium.org
TBR=halliwell@chromium.org
TBR=sky@chromium.org

Bug: None
Change-Id: I4821cd50e926bb1764d861dfe3e4e621185876d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1629170
Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#663284}
13 files changed