Null out member so that it will be properly reset in StartLogging()
Null out member so that it will be properly reset in StartLogging()

r=petersont
Review URL: http://codereview.chromium.org/4242

git-svn-id: http://src.chromium.org/svn/trunk/src@2536 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 8f510f979134a31f3176941234adeef9491a2e3e
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