GitLab

r272290 added a child window to GLSurfaceGLX, but it needs to forward
Expose events to the parent.

BUG=326995
R=ccameron@chromium.org, sadrul@chromium.org

Review URL: https://codereview.chromium.org/299143002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272648 0039d316-1c4b-4281-b951-d872f2087c98