Fix Panel to always detect when a tab is added.

chrome/browser/ui/panels/panel_browser_window_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/ui/panels/panel_browser_window_gtk.h"
 
 #include "base/bind.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/panels/panel.h"
 #include "chrome/browser/ui/panels/panel_manager.h"
@@ skipping 51 matching lines @@
 }
 
 PanelBrowserWindowGtk::~PanelBrowserWindowGtk() {
   if (drag_widget_) {
     // Terminate the grab if we have it. We could do this using any widget,
     // |drag_widget_| is just convenient.
     gtk_grab_add(drag_widget_);
     gtk_grab_remove(drag_widget_);
     DestroyDragWidget();
   }
+  panel_->OnNativePanelClosed();
 }
 
 void PanelBrowserWindowGtk::Init() {
   BrowserWindowGtk::Init();
 
   // Keep the window docked to the bottom of the screen on resizes.
   gtk_window_set_gravity(window(), GDK_GRAVITY_SOUTH_EAST);
 
   // Keep the window always on top.
   gtk_window_set_keep_above(window(), TRUE);
@@ skipping 645 matching lines @@
   }
 }
 
 bool NativePanelTestingGtk::IsWindowSizeKnown() const {
   return panel_browser_window_gtk_->window_size_known_;
 }
 
 bool NativePanelTestingGtk::IsAnimatingBounds() const {
   return panel_browser_window_gtk_->IsAnimatingBounds();
 }