Using the per-revision bisect providing the bisect results,
Good build: 56.0.2924.0 (Revision: 433059).
Bad build: 57.0.2926.0 (Revision: 433437).

You are probably looking for a change made after 433289 (known good), but no later than 433290 (first known bad).
CHANGELOG URL:
  https://chromium.googlesource.com/chromium/src/+log/553e2403263f200cedb4745ca30aa02ff00fa5b0..a5cad337d45510b109937cf71a8a928d3a8022b9

@allada -- Could you please look into the issue, pardon me if it has nothing to do with your changes and if possible please assign it to concern owner.

Thank You.

This was fixed but the fix did not make it onto beta. Can you please confirm this does not work on Canary?

@allada -- Re-checked the issue on Latest Canary# 57.0.2926.0 and the issue is still reproducible.
Hovering on waterfall is chopped after following the steps provided in the issue.

Note: This issue is not seen on Latest Dev# 56.0.2922.1, Latest Beta# 55.0.2883.59 and Latest Stable# 54.0.2840.98.

Please let me know if any more information is needed.
Thank You.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f763518adae729c9fc7296494d7468eee061f519

commit f763518adae729c9fc7296494d7468eee061f519
Author: allada <allada@chromium.org>
Date: Wed Nov 23 02:38:41 2016

[Devtools] Fix hover issue with darktheme in network

This patch fixes dark theme hover issues with dark theme due to
TimelineGrid.js having fixed height for the header draw area.

See: http://imgur.com/a/mWpZu

R=dgozman,lushnikov
BUG= 667170 

Review-Url: https://codereview.chromium.org/2520003006
Cr-Commit-Position: refs/heads/master@{#434092}

[modify] https://crrev.com/f763518adae729c9fc7296494d7468eee061f519/third_party/WebKit/LayoutTests/http/tests/inspector/network/waterfall-images-expected.png
[modify] https://crrev.com/f763518adae729c9fc7296494d7468eee061f519/third_party/WebKit/Source/devtools/front_end/network/NetworkWaterfallColumn.js
[modify] https://crrev.com/f763518adae729c9fc7296494d7468eee061f519/third_party/WebKit/Source/devtools/front_end/network/networkLogView.css
[modify] https://crrev.com/f763518adae729c9fc7296494d7468eee061f519/third_party/WebKit/Source/devtools/front_end/ui_lazy/FlameChart.js
[modify] https://crrev.com/f763518adae729c9fc7296494d7468eee061f519/third_party/WebKit/Source/devtools/front_end/ui_lazy/TimelineGrid.js

Tested the issue on Mac OS 10.11.6 using chrome canary M57 #57.0.2936.0 and issue is fixed. Mouse hover effect on waterfall is seen clear and not chopped.

Hence , adding TE verified labels.

Attached screenshot for reference.

Thanks!

Deleted: 667170.png 285 KB

	667170.png 285 KB View Download