Make DidDestroy a sync IPC so that plugins can properly cleanup.
Make DidDestroy a sync IPC so that plugins can properly cleanup.

BUG=none
TEST=go to youtube with debug pepper flash. quit. check that it doesn't assert that it couldn't save LSOs

Review URL: http://codereview.chromium.org/6791027

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@80356 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