Support dragging panels to stack and snap.

chrome/browser/ui/panels/detached_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/detached_panel_collection.h"
 
 #include <algorithm>
 #include "base/logging.h"
 #include "chrome/browser/ui/panels/panel_drag_controller.h"
 #include "chrome/browser/ui/panels/panel_manager.h"
@@ skipping 187 matching lines @@
   return panels_.find(panel) != panels_.end();
 }
 
 void DetachedPanelCollection::UpdatePanelOnCollectionChange(Panel* panel) {
   panel->set_attention_mode(
       static_cast<Panel::AttentionMode>(Panel::USE_PANEL_ATTENTION |
                                         Panel::USE_SYSTEM_ATTENTION));
   panel->SetAlwaysOnTop(false);
   panel->EnableResizeByMouse(true);
   panel->UpdateMinimizeRestoreButtonVisibility();
+  panel->UpdateStackingProperty();
 }
 
 void DetachedPanelCollection::OnPanelActiveStateChanged(Panel* panel) {
 }
 
 gfx::Point DetachedPanelCollection::GetDefaultPanelOrigin() {
   if (!default_panel_origin_.x() && !default_panel_origin_.y()) {
     gfx::Rect display_area =
         panel_manager_->display_settings_provider()->GetDisplayArea();
     default_panel_origin_.SetPoint(kPanelTilePixels + display_area.x(),
                                    kPanelTilePixels + display_area.y());
   }
   return default_panel_origin_;
 }
 
 void DetachedPanelCollection::ComputeNextDefaultPanelOrigin() {
   default_panel_origin_.Offset(kPanelTilePixels, kPanelTilePixels);
   gfx::Rect display_area =
       panel_manager_->display_settings_provider()->GetDisplayArea();
   if (!display_area.Contains(default_panel_origin_)) {
     default_panel_origin_.SetPoint(kPanelTilePixels + display_area.x(),
                                    kPanelTilePixels + display_area.y());
   }
 }