Support dragging panels to stack and snap.

chrome/browser/ui/gtk/panels/panel_gtk.cc

 // Copyright (c) 2012 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/gtk/panels/panel_gtk.h"
 
 #include <gdk/gdk.h>
 #include <gdk/gdkkeysyms.h>
 #include <X11/XF86keysym.h>
 
@@ skipping 972 matching lines @@
     gtk_window_unstick(window_);
 }
 
 void PanelGtk::EnableResizeByMouse(bool enable) {
 }
 
 void PanelGtk::UpdatePanelMinimizeRestoreButtonVisibility() {
   titlebar_->UpdateMinimizeRestoreButtonVisibility();
 }
 
+void PanelGtk::UpdatePanelStackingProperty() {
+  NOTIMPLEMENTED();
+}
+
 gfx::Size PanelGtk::GetNonClientFrameSize() const {
   GtkAllocation window_allocation;
   gtk_widget_get_allocation(window_container_, &window_allocation);
   GtkAllocation contents_allocation;
   gtk_widget_get_allocation(contents_expanded_, &contents_allocation);
   return gfx::Size(window_allocation.width - contents_allocation.width,
                    window_allocation.height - contents_allocation.height);
 }
 
 void PanelGtk::InvalidateWindow() {
@@ skipping 129 matching lines @@
       break;
     case panel::RESTORE_BUTTON:
       button = titlebar->restore_button();
       break;
     default:
       NOTREACHED();
       return false;
   }
   return gtk_widget_get_visible(button->widget());
 }