Chrome version: 57.0.2929.3 (Official Build)3619fbd7f57a1d171fac4d4adedde499f17eec95-refs/branch-heads/2929@{#3}-32/64 bit
OS: Windows (7,8,10), Mac (10.11.6, 10.12.1), Linux (14.04 LTS) 

Steps:
1. Launch Chrome, open Devtool on NTP and 
2. Click 'Customize and control Devtools'(three dot menu) then 'More tools' and select 'Layers'
3. Right on document screenshot and select 'Show internal layers',now move mouse horizontally on text '#document' towards LHS 
4. Observe.

Actual: Unnecessary hover highlight is seen on upper internal layer text on moving mouse horizontally on text '#document' towards LHS.

Expected:Hover highlight is seen on upper internal layers text on moving mouse horizontally on text '#document' towards LHS.

This is non-regression issue seen from M-57, since this is new feature introduced 57.0.2926.0

Changelog url:
https://chromium.googlesource.com/chromium/src/+log/57.0.2926.0..57.0.2928.0?pretty=fuller&n=10000

Suspecting: r433634 ? 

@caseq, dgozman , Could you please take a look?
 

Deleted: Actual_video.mp4 1.0 MB

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