gl_surface_egl: ensure off and on screen surfaces use the same EGLConfig

ui/base/x/x11_util_internal.h

Index: ui/base/x/x11_util_internal.h
diff --git a/ui/base/x/x11_util_internal.h b/ui/base/x/x11_util_internal.h
index f663fc5ac871b22e28bb3242f7c2b99436328127..22b96b2b4f58d07fb63d4de43dca1835c1cb5378 100644
--- a/ui/base/x/x11_util_internal.h
+++ b/ui/base/x/x11_util_internal.h
@@ -44,6 +44,12 @@ UI_BASE_EXPORT void SetX11ErrorHandlers(XErrorHandler error_handler,
 UI_BASE_EXPORT void LogErrorEventDescription(Display* dpy,
                                              const XErrorEvent& error_event);
 
+// --------------------------------------------------------------------------
+// NOTE: This function cache the results and can be called from any thread.

[piman, 2015/11/20 01:44:41]

This is not true, it can only be called from the UI thread, because that the
only place where it's valid to call into the Display.

[Julien Isorce Samsung, 2015/11/20 09:13:56]

Acknowledged. This will also make the function more consistent with the note on
top of the file: "NOTE: these functions ... UI thread"

+// Select a Visual with preference of alpha support. Compare depth to 32 to
+// know if the returned visual support transparency. NULL parameters is allowed.
+UI_BASE_EXPORT void ChooseARGBVisualForWindow(Visual** visual, int* depth);

[piman, 2015/11/20 01:44:41]

How about ChooseVisualForWindow? It's not guaranteed to be ARGB.

[Julien Isorce Samsung, 2015/11/20 09:13:56]

Make sense.

+
 }  // namespace ui
 
 #endif  // UI_BASE_X_X11_UTIL_INTERNAL_H_