Fixes possible crash in closing window. The sequence when closing a window ends like:
Fixes possible crash in closing window. The sequence when closing a
window ends like:

~TabStrip
~View
~Tab
~Tab::TabContextMenuContents
~TabStrip::TabContextMenuContents
TabStrip::StopAllHighlighting

This is problematic as StopAllHighlighting references objects whose
destructor has already run. This crashes on Linux, but not on windows
(probably because of different implementation of stl).

I've fixed this by deleting all child views from ~TabStrip so that if
they end up calling into the TabStrip every is still valid.

BUG=none
TEST=create a couple of tabs, bring up the context menu for each,
     close the context menu, close the window and make sure you don't get a
     crash. Be sure and test this on both windows and Chrome OS.

Review URL: http://codereview.chromium.org/505066

git-svn-id: http://src.chromium.org/svn/trunk/src@35151 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 841d122a7ce6e6b259f5ea4e58444d958e226896
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser