Workaround a race condition caused by not synchronization destruction of the pipeline.
Workaround a race condition caused by not synchronization destruction of the pipeline.

BUG=16059
TEST=none

Review URL: http://codereview.chromium.org/171018

git-svn-id: http://src.chromium.org/svn/trunk/src@23514 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 001406e95184d7ca63be2b55845bfa7885fcbde1
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