GTK: Create the start of a compatibility header wrapping deprecated methods.

chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc

Index: chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc
diff --git a/chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc b/chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc
index fe528fef364598594296f9de0959bf6235d1bc11..a6259b89fa327880b39cdda6efa5e87c8a12e57a 100644
--- a/chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc
+++ b/chrome/browser/ui/gtk/tabs/tab_strip_gtk.cc
@@ -34,6 +34,7 @@
 #include "ui/base/animation/animation_delegate.h"
 #include "ui/base/animation/slide_animation.h"
 #include "ui/base/dragdrop/gtk_dnd_util.h"
+#include "ui/base/gtk/gtk_compat.h"
 #include "ui/base/gtk/gtk_screen_utils.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/gtk_util.h"
@@ -1611,7 +1612,7 @@ bool TabStripGtk::IsCursorInTabStripZone() const {
 }
 
 void TabStripGtk::ReStack() {
-  if (!GTK_WIDGET_REALIZED(tabstrip_.get())) {
+  if (!gtk_widget_get_realized(tabstrip_.get())) {
     // If the window isn't realized yet, we can't stack them yet. It will be
     // done by the OnMap signal handler.
     return;