Chrome Version: 56.0.2899.0 (Official Build) bb7071018e1fd8bf223b8ffff660883b7d17278d-refs/heads/master@{#426989} 32/64-bit.
OS: Windows (7,8,8.1,10),Linux (14.04 LTS),Mac OS X(10.10.5, 10.11.4).

What steps will reproduce the problem?
1. Launch chrome and navigate to chrome://md-settings page.
2. Click on 'Main menu' icon at top LHS to open it.
3. Now, press 'Tab' key from keyboard and observe the focus.

Focus doesn't traverse through main menu options.
Focus should traverse through main menu options. 

This is a regression issue, broken in M-53 series, below is maual regression range.

Good build: 53.0.2769.2 
Bad build: 53.0.2770.0 

Narrow bisect:
https://chromium.googlesource.com/chromium/src/+log/bf041ce47b52b0c2ef12d316d47b29ce44cd4804..caddfab84c60dbd9a8ace2ff146115696620d3c2?pretty=fuller&n=10

Suspecting: r400284

Kindly review the attached screen-cast for reference.
 

Deleted: Actual behavior.mp4 818 KB

	Actual behavior.mp4 818 KB View Download