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..d5c598b7235c6e0257926442a4057ff242c1fce0 100644
--- a/ui/base/x/x11_util_internal.h
+++ b/ui/base/x/x11_util_internal.h
@@ -44,6 +44,15 @@ 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 on compositing window
+// managers. The caller must compare depth to 32 to know if the returned visual
+// supports transparency. NULL parameters are allowed to install or query the
+// cached visual and depth.
+#if !defined(OS_CHROMEOS)
+UI_BASE_EXPORT void ChooseVisualForWindow(Visual** visual, int* depth);
+#endif
+
 }  // namespace ui
 
 #endif  // UI_BASE_X_X11_UTIL_INTERNAL_H_