Is this an IPC message or something happening solely within the renderer? If it's an IPC message that we could remove it would be great to prioritize its removal.

It's is triggered by an IPC message from the browser, but I don't know if we can remove the entire message or just the cc=>main thread hop (which is almost as expensive as an IPC)

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Still there.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4d60b40e28c03273690c45f70e6fd9a53f8449f4

commit 4d60b40e28c03273690c45f70e6fd9a53f8449f4
Author: Karolina Soltys <ksolt@chromium.org>
Date: Mon Oct 01 19:28:20 2018

Removed several levels of calls to RenderWidget::DidReceiveCompositorFrameAck.

Bug:  725061 
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I9bec1e76635379dd7a09a5160e1dff69074692f9
Reviewed-on: https://chromium-review.googlesource.com/1183232
Reviewed-by: Camille Lamy <clamy@chromium.org>
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Commit-Queue: Karolina Soltys <ksolt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595498}
[modify] https://crrev.com/4d60b40e28c03273690c45f70e6fd9a53f8449f4/cc/trees/layer_tree_host_unittest.cc
[modify] https://crrev.com/4d60b40e28c03273690c45f70e6fd9a53f8449f4/cc/trees/layer_tree_settings.h
[modify] https://crrev.com/4d60b40e28c03273690c45f70e6fd9a53f8449f4/cc/trees/proxy_impl.cc
[modify] https://crrev.com/4d60b40e28c03273690c45f70e6fd9a53f8449f4/cc/trees/proxy_impl.h
[modify] https://crrev.com/4d60b40e28c03273690c45f70e6fd9a53f8449f4/cc/trees/single_thread_proxy.cc
[modify] https://crrev.com/4d60b40e28c03273690c45f70e6fd9a53f8449f4/content/renderer/gpu/layer_tree_view.cc
[modify] https://crrev.com/4d60b40e28c03273690c45f70e6fd9a53f8449f4/content/renderer/gpu/layer_tree_view.h
[modify] https://crrev.com/4d60b40e28c03273690c45f70e6fd9a53f8449f4/content/renderer/gpu/layer_tree_view_delegate.h
[modify] https://crrev.com/4d60b40e28c03273690c45f70e6fd9a53f8449f4/content/renderer/render_widget.cc
[modify] https://crrev.com/4d60b40e28c03273690c45f70e6fd9a53f8449f4/content/renderer/render_widget.h
[modify] https://crrev.com/4d60b40e28c03273690c45f70e6fd9a53f8449f4/content/test/stub_layer_tree_view_delegate.h