Use active window if on current workspace for fullscreen mode.

ash/switchable_windows.cc

 // 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.
 
 #include "ash/switchable_windows.h"
 
 #include "ash/shell_window_ids.h"
+#include "ui/aura/window.h"
 
 namespace ash {
 
 const int kSwitchableWindowContainerIds[] = {
   internal::kShellWindowId_DefaultContainer,
   internal::kShellWindowId_AlwaysOnTopContainer,
   internal::kShellWindowId_PanelContainer
 };
 
 const size_t kSwitchableWindowContainerIdsLength =
     arraysize(kSwitchableWindowContainerIds);
 
+bool IsSwitchableContainer(const aura::Window* window) {
+  if (!window)
+    return false;
+  for (size_t i = 0; i < kSwitchableWindowContainerIdsLength; ++i) {
+    if (window->id() == kSwitchableWindowContainerIds[i])
+      return true;
+  }
+  return false;
+}
+
 }  // namespace ash