GTK: Closing in on being completely GSEALed.

ui/base/gtk/gtk_compat.h

Index: ui/base/gtk/gtk_compat.h
diff --git a/ui/base/gtk/gtk_compat.h b/ui/base/gtk/gtk_compat.h
index 3c3b29f4332413d65bd39975e66d55174c9a04bf..b0c59e139fc768a84fc8887e1ca92e188d0a11a5 100644
--- a/ui/base/gtk/gtk_compat.h
+++ b/ui/base/gtk/gtk_compat.h
@@ -56,6 +56,10 @@ inline void gtk_widget_style_attach(GtkWidget* widget) {
 #endif  // !GTK_CHECK_VERSION(2, 20, 0) || defined(GOOGLE_CHROME_BUILD)
 
 #if !GTK_CHECK_VERSION(2, 22, 0)
+inline GdkWindow* gdk_drag_context_get_source_window(GdkDragContext *context) {
+  return context->source_window;
+}
+
 inline gint gdk_visual_get_depth(GdkVisual* visual) {
   return visual->depth;
 }