Add lock since the add/remove tabproxy is invoked from different threads. BUG=53963 Review URL: http://codereview.chromium.org/3306003
Add lock since the add/remove tabproxy is invoked from different threads.
BUG=53963
Review URL: http://codereview.chromium.org/3306003

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@58367 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