Ensure GL initialization only happens once, and provide common init path

ui/aura/demo/demo_main.cc

Index: ui/aura/demo/demo_main.cc
diff --git a/ui/aura/demo/demo_main.cc b/ui/aura/demo/demo_main.cc
index 3dcd7db3b0244853a2b49fed71d4c61b74c6cbf1..7739ed58c8a200adad8dd9329089960b8ccda219 100644
--- a/ui/aura/demo/demo_main.cc
+++ b/ui/aura/demo/demo_main.cc
@@ -21,6 +21,7 @@
 #include "ui/events/event.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/rect.h"
+#include "ui/gl/gl_surface.h"
 
 #if defined(USE_X11)
 #include "base/message_loop/message_pump_x11.h"
@@ -108,6 +109,8 @@ int DemoMain() {
   // Create the message-loop here before creating the root window.
   base::MessageLoopForUI message_loop;
 
+  gfx::GLSurface::InitializeOneOff();
+
   // The ContextFactory must exist before any Compositors are created.
   bool allow_test_contexts = false;
   ui::InitializeContextFactoryForTests(allow_test_contexts);