Take 2: make bubble more tolerant of notification order when quitting.
Take 2: make bubble more tolerant of notification order when quitting.

BUG=37807

TEST=\
Run a debug build of Chrome like this:  
  NSZombieEnabled=YES xcodebuild/Debug/Chromium.app/Contents/MacOS/Chromium 
Open a bubble then Cmd-Q.
Make sure you don't see a line like this:
  2010-03-10 19:24:20.381 Chromium[73024:903] *** -[ChromeBrowserWindow removeChildWindow:]: message sent to deallocated instance 0x18f8b2a0
Repeat 20 times.

Review URL: http://codereview.chromium.org/851005

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@41373 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser