Chrome Version: 66.0.3357.0 (Official Build) Revision 837639b937d3d1a084c246258ad1f460e4f0f68e-refs/heads/master@{#539659} (32/64-bit)
OS: Windows(7,8,8.1,10), Linux(14.04 LTS).

What steps will reproduce the problem?
1. Launch Chrome, open NTP and click on mic icon in 'Search Google or type URL' textbox.
2. Click on Allow/Block button on microphone bubble such that microphone icon appears in omnibox.
3. Click on microphone icon in omnibox to open the bubble, click to open 'Microphone' drop-down list and observe.

Actual: Right side border of drop-down list seems to be chopped.
Expected: Right side border of drop-down list should seen properly.

This is a regression issue, broken in M-65 series, below is manual regression range:

Good build: 65.0.3286.0 (Revision: 521957)
Bad build: 65.0.3287.0 (Revision: 522139)

Using the per-revision bisect providing the bisect results:

You are probably looking for a change made after 522118 (known good), but no later than 522119 (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/3425c94e632ca511ad9dcf7c1c4e3b49fcfcf0dc..12d3545cdca172bf6e8f1fb7e831a2d12c916f26

Suspecting: https://chromium.googlesource.com/chromium/src/+/12d3545cdca172bf6e8f1fb7e831a2d12c916f26

@ellyjones: 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.

NOTE: 
1. This issue is not reproducible on M-65 Beta (build # 65.0.3325.106) but it is reproducible on M-66 Dev(build # 66.0.3355.0).
2. This issue is not reproducible on Mac(10.12.6, 10.13.1,10.13.4) OS.

Kindly review the attached screen-cast for reference.

Thank you.
 

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	Actual behavior.mp4 390 KB View Download

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	Expected behavior.mp4 206 KB View Download