Chrome Version: 69.0.3449.0 (Official Build) (64-bit) 4c662013d5fa1e3a073c4e2a62844d6838d152d3-refs/branch-heads/3449@{#1}
OS: Mac 10.13.1(Desktop), 10.13.6(Macbook Pro Touchbar).

What steps will reproduce the problem?
1. Launch Chrome, Open DevTools and undock it into separate window.
2. Press “Command+Shift+D” to restore the DevTools to it's last position(dock to right).
3. Now again press “Command+Shift+D” to undock it into separate window and observe.

Actual: DevTools windows gets blank.
Expected: DevTools window should not blank.

This is a regression issue, broken in M-69 series, below is manual regression range.

Good build: 69.0.3447.0 (Revision: 563479)
Bad build: 69.0.3448.0 (Revision: 563958)

Using the per-revision bisect providing the bisect results:

You are probably looking for a change made after 563957 (known good), but no later than 563958 (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/8fd698baad2716d78d3d4cc25fdd7694fa3c2422..07a1071502f4699d445d0b7f46f3ca27d10efef0

Suspecting: https://chromium.googlesource.com/chromium/src/+/07a1071502f4699d445d0b7f46f3ca27d10efef0

@sdy: 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.

NOTE: This issue is not reproducible on Mac(10.12.6), Win(7,8,8.1,10) & Linux (14.04 LTS) OS.

Kindly review the attached screen-cast for reference.

Thank you.
 

Deleted: Actual behavior.mov 3.8 MB

	Actual behavior.mov 3.8 MB View Download

Deleted: Expected behavior.mov 3.1 MB

	Expected behavior.mov 3.1 MB View Download