Aura desktop: Fix tab dragging within a single chrome window.

ui/base/x/x11_util.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 UI_BASE_X_X11_UTIL_H_
 #define UI_BASE_X_X11_UTIL_H_
 #pragma once
 
 // This file declares utility functions for X11 (Linux only).
 //
@@ skipping 170 matching lines @@
 
  protected:
   virtual ~EnumerateWindowsDelegate() {}
 };
 
 // Enumerates all windows in the current display.  Will recurse into child
 // windows up to a depth of |max_depth|.
 UI_EXPORT bool EnumerateAllWindows(EnumerateWindowsDelegate* delegate,
                                    int max_depth);
 
+// Enumerates the top-level windows of the current display.
+UI_EXPORT void EnumerateTopLevelWindows(ui::EnumerateWindowsDelegate* delegate);
+
 // Returns all children windows of a given window in top-to-bottom stacking
 // order.
 UI_EXPORT bool GetXWindowStack(XID window, std::vector<XID>* windows);
 
 // Restack a window in relation to one of its siblings.  If |above| is true,
 // |window| will be stacked directly above |sibling|; otherwise it will stacked
 // directly below it.  Both windows must be immediate children of the same
 // window.
 void RestackWindow(XID window, XID sibling, bool above);
 
@@ skipping 89 matching lines @@
 
  private:
   char* string_;
 
   DISALLOW_COPY_AND_ASSIGN(XScopedString);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_X_X11_UTIL_H_