The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/21e06c688bca3bdcb00b3ec9549989bb0d72c297

commit 21e06c688bca3bdcb00b3ec9549989bb0d72c297
Author: erikchen <erikchen@chromium.org>
Date: Thu Aug 30 19:24:43 2018

Add heap profiling support for utility processes.

This CL adds two new heap profiling modes: "utility-sampling" and
"utility-and-browser". The former mode will profile all utility processes at
startup, with 1/3 probability. The latter will profile all utility processes and
the browser process [currently just useful for tests].

In addition to some small plumbing and tests, this CL modifies
UtilityThreadImpl::Init to call
"GetContentClient()->OnServiceManagerConnected(connection);". The callback
OnServiceManagerConnected() was not getting propagated to the
ChromeContentClient in the utility process [this was a bug].

The profiling process itself is a utility process and must never be profiled --
that will cause deadlock. This is avoided by adding an early out to
Client::StartProfiling for the utility process. The newly added tests confirm
that we don't deadlock even when attempting to profile all utility processes.

Change-Id: I74e2921d7ceff6150080c182db756be9ac0d076b
Bug:  878431 
Reviewed-on: https://chromium-review.googlesource.com/1195836
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587699}
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/chrome/android/javatests/src/org/chromium/chrome/browser/profiling_host/ProfilingProcessHostAndroidTest.java
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/chrome/browser/profiling_host/memlog_browsertest.cc
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/chrome/browser/ui/webui/memory_internals_ui.cc
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/components/heap_profiling/client_connection_manager.cc
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/components/heap_profiling/test_driver.cc
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/components/services/heap_profiling/DEPS
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/components/services/heap_profiling/public/cpp/BUILD.gn
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/components/services/heap_profiling/public/cpp/client.cc
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/components/services/heap_profiling/public/cpp/settings.cc
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/components/services/heap_profiling/public/cpp/settings.h
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/components/services/heap_profiling/public/cpp/switches.cc
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/components/services/heap_profiling/public/cpp/switches.h
[modify] https://crrev.com/21e06c688bca3bdcb00b3ec9549989bb0d72c297/content/utility/utility_thread_impl.cc

We have the ability to turn on this experiment anytime we want for utility processes, on any platforms.

We've been running heap profiling in the utility process.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5d841ddad587ec2a53c369fbf9ec9947ea2c2721

commit 5d841ddad587ec2a53c369fbf9ec9947ea2c2721
Author: erikchen <erikchen@chromium.org>
Date: Thu Oct 25 20:05:37 2018

Add a utility process threshold for memlog uploads.

Without the threshold, memlog reports will never be uploaded for profiled
utility processes.

Bug:  878431 
Change-Id: I63fba01d45c2427859c5227d527bae8d6791e0e0
Reviewed-on: https://chromium-review.googlesource.com/c/1299656
Commit-Queue: Erik Chen <erikchen@chromium.org>
Reviewed-by: ssid <ssid@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602835}
[modify] https://crrev.com/5d841ddad587ec2a53c369fbf9ec9947ea2c2721/chrome/browser/profiling_host/background_profiling_triggers.cc

Also we're enabling it for a single renderer process for 1% of Canary population. I need to keep this bug open for Finch experiment review.