Refactor most recently used window tracking into a separate class.

ash/focus_cycler.cc

 // 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.
 
 #include "ash/focus_cycler.h"
 
 #include "ash/shell.h"
+#include "ash/wm/mru_window_tracker.h"
 #include "ash/wm/window_cycle_controller.h"
 #include "ash/wm/window_util.h"
 #include "ui/aura/client/activation_client.h"
 #include "ui/aura/window.h"
 #include "ui/views/accessible_pane_view.h"
 #include "ui/views/focus/focus_search.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 
 namespace {
 
 bool HasFocusableWindow() {
-  return !WindowCycleController::BuildWindowList(NULL, false).empty();
+  return !MruWindowTracker::BuildWindowList(NULL, false).empty();
 }
 
 }  // namespace
 
 namespace internal {
 
 FocusCycler::FocusCycler() : widget_activating_(NULL) {
 }
 
 FocusCycler::~FocusCycler() {
@@ skipping 73 matching lines @@
   // will be taken care of by the widget activation.
   widget_activating_ = widget;
   widget->Activate();
   widget_activating_ = NULL;
   return widget->IsActive();
 }
 
 }  // namespace internal
 
 }  // namespace ash