Support dragging panels to stack and snap.

chrome/browser/ui/cocoa/panels/panel_cocoa.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_COCOA_PANELS_PANEL_COCOA_H_
 #define CHROME_BROWSER_UI_COCOA_PANELS_PANEL_COCOA_H_
 
 #import <Foundation/Foundation.h>
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/ui/panels/native_panel.h"
@@ skipping 34 matching lines @@
   virtual void HandlePanelKeyboardEvent(
       const content::NativeWebKeyboardEvent& event) OVERRIDE;
   virtual void FullScreenModeChanged(bool is_full_screen) OVERRIDE;
   virtual bool IsPanelAlwaysOnTop() const OVERRIDE;
   virtual void SetPanelAlwaysOnTop(bool on_top) OVERRIDE;
   virtual void EnableResizeByMouse(bool enable) OVERRIDE;
   virtual void UpdatePanelMinimizeRestoreButtonVisibility() OVERRIDE;
   virtual void PanelExpansionStateChanging(
       Panel::ExpansionState old_state,
       Panel::ExpansionState new_state) OVERRIDE;
+  virtual void UpdatePanelStackingProperty() OVERRIDE;
   virtual void AttachWebContents(content::WebContents* contents) OVERRIDE;
   virtual void DetachWebContents(content::WebContents* contents) OVERRIDE;
 
   // These sizes are in screen coordinates.
   virtual gfx::Size WindowSizeFromContentSize(
       const gfx::Size& content_size) const OVERRIDE;
   virtual gfx::Size ContentSizeFromWindowSize(
       const gfx::Size& window_size) const OVERRIDE;
   virtual int TitleOnlyHeight() const OVERRIDE;
 
@@ skipping 30 matching lines @@
   // True if the panel should always stay on top of other windows.
   bool always_on_top_;
 
   bool is_shown_;  // Panel is hidden on creation, Show() changes that forever.
   NSInteger attention_request_id_;  // identifier from requestUserAttention.
 
   DISALLOW_COPY_AND_ASSIGN(PanelCocoa);
 };
 
 #endif  // CHROME_BROWSER_UI_COCOA_PANELS_PANEL_COCOA_H_