Chrome version : 51.0.2693.2 255cb9d4b581ae3eb9a5b582175bc18c7997a741-refs/branch-heads/2693@{#2} 32/64 bit
OS : Windows (Win 7 aero enabled), Linux

Steps : 
1. Launch chrome, go to chrome://tracing and click anywhere inside the tracing window.
2. Now press Shift + Tab key twice to move focus in backward direction and observe.

Actual : Focus is lost after pressing Shift + Tab key twice.
Expected : Focus should not be lost on pressing Shift + Tab key.

This is a regression issue broken in 'M-44' and below is the manual regression and narrow bisect info.
Good Build :  44.0.2358.0
Bad Build :  44.0.2360.0

Narrow Bisect : 
https://chromium.googlesource.com/chromium/src/+log/607ed17ba5d0d1c67901ecc7160db660f08bd831..168a20642b1ceb7fb49e78417671aaec26f5477a?pretty=fuller&n=10000

Suspecting : r324192 from narrow bisect

@nednguyen : Could you please help to reassign if your change is not the cause for this issue.

Note : Above issue is not seen on Mac OS.
 

Deleted: Actual_tracing_focus.mp4 498 KB

Actual_tracing_focus.mp4 498 KB Download

Deleted: Expected_tracing_focus.mp4 577 KB

Expected_tracing_focus.mp4 577 KB Download