Make panel adjust bounds per preferred size change notification on Windows.

chrome/browser/tab_contents/tab_contents_view_gtk.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/tab_contents/tab_contents_view_gtk.h"
 
 #include <gdk/gdk.h>
 #include <gdk/gdkkeysyms.h>
 #include <gtk/gtk.h>
 
@@ skipping 236 matching lines @@
 }
 
 void TabContentsViewGtk::RestoreFocus() {
   if (focus_store_.widget())
     gtk_widget_grab_focus(focus_store_.widget());
   else
     SetInitialFocus();
 }
 
 void TabContentsViewGtk::UpdatePreferredSize(const gfx::Size& pref_size) {
+  if (tab_contents_->delegate())
+    tab_contents_->delegate()->UpdatePreferredSize(tab_contents_, pref_size);
 }
 
 bool TabContentsViewGtk::IsDoingDrag() const {
   return false;
 }
 
 void TabContentsViewGtk::CancelDragAndCloseTab() {
 }
 
 bool TabContentsViewGtk::IsEventTracking() const {
@@ skipping 237 matching lines @@
   g_value_set_int(&value, child_x);
   gtk_container_child_set_property(GTK_CONTAINER(floating_container),
                                    widget, "x", &value);
 
   int child_y = std::max((allocation->height - requisition.height) / 2, 0);
   g_value_set_int(&value, child_y);
   gtk_container_child_set_property(GTK_CONTAINER(floating_container),
                                    widget, "y", &value);
   g_value_unset(&value);
 }