Fixed null dereference when GPU ContextGroup failed to initialize.
Fixed null dereference when GPU ContextGroup failed to initialize.

TEST=try
BUG=55925

Review URL: http://codereview.chromium.org/3592006

git-svn-id: http://src.chromium.org/svn/trunk/src@61539 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 8b92573c0a807d93dd9ead89da92634149f67b8f
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