Using the per-revision bisect providing the bisect results,
Good build: 63.0.3221.0 (Revision: 503309).
Bad build: 63.0.3222.0 (Revision: 503582).

You are probably looking for a change made after 503577 (known good), but no lat
er than 503578 (first known bad).

CHANGELOG URL:

The script might not always return single CL as suspect as some perf builds might get missing due to failure.

https://chromium.googlesource.com/chromium/src/+log/ba35577855190826b59b6795963d32cc4fdb86aa..98a273dbd384790979baed706eb8907435654314

From the CL above, assigning the issue to the concern owner 

@varkha- Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.

Suspect : https://chromium.googlesource.com/chromium/src/+/98a273dbd384790979baed706eb8907435654314

Thanks!

Thanks for filing this. Trying to understand this better - is the complaint here that the buttons are too close and the ripple effect circles overlap when pressed or clicked (as opposed to anything in how the bubble actually behaves)?

As a point of reference - do you see the exact same behavior on a find in page bubble?

+ bettes@ for comment on possibly spacing the controls differently.
Dropping to Pri-2 based on my possibly wrong understanding of what the issue here is.

This is acceptable behavior given that the - and + will never (or rarely) be selected at the same time. Marking as wontFix. Thanks!