Use the lock when accessing the buffer object.
Use the lock when accessing the buffer object.

BUG=69195
TEST=play Z-Type for hours :)

Review URL: http://codereview.chromium.org/6157007

git-svn-id: http://src.chromium.org/svn/trunk/src@71211 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: b911325e4c5f74cd0797f97f10e9d927ae4486f9
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