Closing Chrome 49 shows a messagebox with high probability about broken gaia_auth manifest

I can not make the bug happen with the old Chrome 40.0.2214.115
But the bug happens with high probability (!=100%) when closing the chrome.exe process of either
Chrome 49.0.2623.110
or
Chrome 49.0.2623.112 (last XP compatible version).

Reproduction steps

• just run the Chrome installer and at the end of the setup it will run the chrome.exe itself
• now close the chrome window via the top-right-x in titlebar

Expected result
the browser window should close without any messagebox with 100% chance
( no chrome.exe processes should remain in taskmgr, see CORE-14185 for that)
neither Windows XPSP3 nor 2k3sp2 do show that box

Observed result
high chance for the gaia_auth manifest message-box
0.4.15-dev-2923-g2210d23_gaia.png
0.4.15-dev-2923-g2210d23_gaia.log
( the chrome.exe process remains sitting in taskmgr, see CORE-14185 for that)

Sidenote
I can make it happen with 0.4.15-dev-2923-g2210d23 and also with 0.4.14-RC-96-g08352ec. It is nothing new, it happened as long as we were capable to 'run' those new Chrome versions at all.