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..31b6c92708f7b656b024e9d25a1660d394911dfa 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);
 
+// --------------------------------------------------------------------------
+// Selects a Visual with a preference for alpha support. The caller must compare

[Corentin Wallez, 2015/11/22 04:09:01]

nit: The preference for alpha support is only on compositing window managers.

[Julien Isorce Samsung, 2015/11/23 08:28:03]

Acknowledged.

+// depth to 32 to know if the returned visual supports transparency. NULL
+// parameters are allowed to install or query the cached visual and depth.
+UI_BASE_EXPORT void ChooseVisualForWindow(Visual** visual, int* depth);
+
 }  // namespace ui
 
 #endif  // UI_BASE_X_X11_UTIL_INTERNAL_H_