Support creating virtual contexts.
This creates virtual contexts within a GLShareGroup, when
'--enable-virtual-gl-contexts' is given on the command line.
It requires the shared real GL context, which is created
from the default offscreen surface configuration, to be compatible
with any surface that is made current with a virtual context.
BUG=160710
Review URL: https://chromiumcodereview.appspot.com/11308151
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170148 0039d316-1c4b-4281-b951-d872f2087c98
14 files changed
