Chrome/Chromium browsers do not properly terminate upon closing

VBox 4.3.40
reactos gcc dbg 0.4.8-dev-641-g79d392c
http://www.filepuma.com/download/google_chrome_32bit_37.0.2062.124-6932/download/

install Chrome
start Chrome, let the GUI appear
close the program via top-right-closing-x in title-bar

Expected behavior:
the GUI vanishes properly and the process chrome.exe vanishes in taskmgr

Observed behavior:
the GUI vanishes properly but the process chrome.exe persists in taskmgr

This is problematic because we can not start a new Chrome session before killing the previous instance in the taskmgr explicitly.

About the last 10-20lines in 0.4.8dev-641.log were logged after I pressed the top-right-closing-x in titlebar. I don't think any line is related, not even the JobObject one.
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Some additional observations:

• Alternative shutdown path (closing every tab in the browser including the last one) leads to the same issue
• All Chrome / Chromium and SRWare Iron versions I have tested (from very early builds up to their newest) seem to be affected by this, which means you can most likely debug using whichever version is most appealing to you (symbols & co)
• Both: Portable & installable Chrome/Chromium are affected
• We have no recent ros regression here, I can see this 0.4.8dev down to 0.4.1rls at least (did not test further down)
• When the zombie-process is in endless wait-state,
  In Chrome 37 the CPU usage stays at 100% for chrome.exe (busywait),
  contrary for early Chromium builds the CPU usage is 0% for chrome.exe (idlewait)
• It does not matter whether cmd-line-option --no-sandbox is passed or not (to allow Chrome browsing)

I consider the ticket being resolved when linked Chrome 37.0.2062.124 can be closed properly.