Chrome Version: 42.0.2311.13
OS: Chrome OS, Platform 6812.9.0
Device: Chromebook Pixel 1 (LINK)

What steps will reproduce the problem?
(1) Get ChromeOS R42-6812.9.0 (gs://chromeos-releases/dev-channel/link/6812.9.0/ChromeOS-test-R42-6812.9.0-link.tar.xz) and install this in LINK board.
(2) Add --trace-startup --trace-startup-file=/tmp/trace.json --trace-startup-duration=5 to /etc/chrome_dev.conf
(3) Sign in, and then Sign out and time the "black screen" before the login prompt reappears.
(4) Sign in, and then change a flag in chrome://flags and click the "Restart" button. Time the "black screen" before chrome reappears.
(5) Do the same thing with the previous version (R42-6812.8.0, gs://chromeos-releases/dev-channel/link/6812.8.0/ChromeOS-test-R42-6812.8.0-link.tar.xz)
(6) Compare the black screen time: version 6812.9.0 takes almost 2 seconds longer than 6812.8.0. More detail of the startup bottleneck can be seen in the trace.json file. The suspected bottlenecks are "ShowLoginWebUI:WaitForScreenStateInitialize" and "CompositorResizeLock".


What is the expected result? Chrome restart or sign out time shouldn't take much significantly longer than the previous version.

What happens instead? Chrome restart and sign out time takes much significantly longer than the previous version.