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 186 matching lines @@
 bool DetachedPanelCollection::HasPanel(Panel* panel) const {
   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();

[Dmitry Titov, 2013/01/10 00:16:24]

This is where I would add a new method on Panel,
UpdateOnCollectionChange(new_collection_type) and put both calls to
UpdateMinimizeRestoreButtonVisibility() and UpdateStackingProperty() in it.
Otherwise we'll end up calling the same pack of Update...() methods from every
Collection... 
Also, I'd call it from the same place that calls
PanelColelction::UpdatePanelOnColelctionChange().

[jianli, 2013/01/10 02:05:37]

Changed to adding new method OnCollectionChanged() as suggested.

+  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());
   }
 }