Support dragging panels to stack and snap.

chrome/browser/ui/panels/docked_panel_collection.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/panels/docked_panel_collection.h"
 
 #include <math.h>
 
 #include <algorithm>
 #include <vector>
@@ skipping 725 matching lines @@
   for (Panels::reverse_iterator iter = panels_copy.rbegin();
        iter != panels_copy.rend(); ++iter)
     (*iter)->Close();
 }
 
 void DockedPanelCollection::UpdatePanelOnCollectionChange(Panel* panel) {
   panel->set_attention_mode(Panel::USE_PANEL_ATTENTION);
   panel->SetAlwaysOnTop(true);
   panel->EnableResizeByMouse(true);
   panel->UpdateMinimizeRestoreButtonVisibility();
+  panel->UpdateStackingProperty();
 }
 
 void DockedPanelCollection::ScheduleLayoutRefresh() {
   refresh_action_factory_.InvalidateWeakPtrs();
   MessageLoop::current()->PostDelayedTask(FROM_HERE,
       base::Bind(&DockedPanelCollection::RefreshLayout,
                  refresh_action_factory_.GetWeakPtr()),
       base::TimeDelta::FromMilliseconds(PanelManager::AdjustTimeInterval(
           kRefreshLayoutAfterActivePanelChangeDelayMs)));
 }
 
 void DockedPanelCollection::OnPanelActiveStateChanged(Panel* panel) {
   // Refresh layout, but wait till active states settle.
   // This lets us avoid refreshing too many times when one panel loses
   // focus and another gains it.
   ScheduleLayoutRefresh();
 }
 
 bool DockedPanelCollection::HasPanel(Panel* panel) const {
   return find(panels_.begin(), panels_.end(), panel) != panels_.end();
 }