The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/74d6daa145a14c8699f50dda6fb8f20831865bb4

commit 74d6daa145a14c8699f50dda6fb8f20831865bb4
Author: Nicolas Pena <npm@chromium.org>
Date: Tue Jul 03 15:57:49 2018

Report ExpectedQueueingTime on renderers without main frames

This CL adds a histogram to record EQT on renderer processes that do not
host main frames:
RendererScheduler.ExpectedTaskQueueingDurationWithoutMainFrame

While at it, fix a typo introduced in 5ec2058 in histograms.xml.

Bug:  829796 
Change-Id: I05b3ce7a7cd3eb5432ce4f54eb54bf7100816b97
Reviewed-on: https://chromium-review.googlesource.com/1120778
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Timothy Dresser <tdresser@chromium.org>
Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572239}
[modify] https://crrev.com/74d6daa145a14c8699f50dda6fb8f20831865bb4/third_party/blink/renderer/platform/scheduler/main_thread/main_thread_scheduler_impl.cc
[modify] https://crrev.com/74d6daa145a14c8699f50dda6fb8f20831865bb4/tools/metrics/histograms/histograms.xml

Do we want splits for these renderers as well or not at the moment?

I'd say lets not bother for now, unless we have a concrete use case.