Fix UMR caused by ActiveWindowWatcher.
Fix UMR caused by ActiveWindowWatcher.

As spotted by the valgrind ui_tests buildbot.

BUG=16473

Review URL: http://codereview.chromium.org/149486


git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@20428 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