Attach panel while dragging to bring it in front of other panels.

ash/wm/workspace/workspace.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 ASH_WM_WORKSPACE_WORKSPACE_H_
 #define ASH_WM_WORKSPACE_WORKSPACE_H_
 
 #include <vector>
 
 #include "ash/ash_export.h"
@@ skipping 29 matching lines @@
   // recently activated window in the workspace.
   aura::Window* GetTopmostActivatableWindow();
 
   // Resets state. This should be used before destroying the Workspace.
   aura::Window* ReleaseWindow();
 
   bool is_maximized() const { return is_maximized_; }
 
   aura::Window* window() { return window_; }
 
+  WorkspaceEventHandler* event_handler() { return event_handler_.get(); }
+
   const WorkspaceLayoutManager* workspace_layout_manager() const {
     return workspace_layout_manager_;
   }
   WorkspaceLayoutManager* workspace_layout_manager() {
     return workspace_layout_manager_;
   }
 
   const WorkspaceManager* workspace_manager() const {
     return workspace_manager_;
   }
@@ skipping 20 matching lines @@
 
   WorkspaceLayoutManager* workspace_layout_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(Workspace);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_WORKSPACE_WORKSPACE_H_