Use active window if on current workspace for fullscreen mode.

ash/switchable_windows.h

 // Copyright 2014 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_SWITCHABLE_WINDOWS_H_
 #define ASH_SWITCHABLE_WINDOWS_H_
 
 #include "ash/ash_export.h"
 #include "base/macros.h"
 
+namespace aura {
+  class Window;
+}
+
 namespace ash {
 
 // List of containers which contain windows that can be switched via Alt+Tab to.
 ASH_EXPORT extern const int kSwitchableWindowContainerIds[];
 
 // The number of elements in kSwitchableWindowContainerIds.
 ASH_EXPORT extern const size_t kSwitchableWindowContainerIdsLength;
 
+// Returns true if |window| is a container for windows which can be switched to.
+ASH_EXPORT bool IsSwitchableContainer(const aura::Window* window);
+
 }  // namespace ash
 
 #endif  // ASH_SWITCHABLE_WINDOWS_H_