Keep the mouse cursor within desktop

ash/monitor/multi_monitor_manager.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/monitor/multi_monitor_manager.h"
 
 #include <string>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 27 matching lines @@
 using std::vector;
 using aura::Monitor;
 using aura::RootWindow;
 using aura::Window;
 
 MultiMonitorManager::MultiMonitorManager() {
   Init();
 }
 
 MultiMonitorManager::~MultiMonitorManager() {
-  // All monitors must have been deleted when monitor manager is deleted.
-  CHECK(!monitors_.size());
+  // All monitors must have been deleted when root windows are deleted.
+  DCHECK(!monitors_.size());
 }
 
 // static
 void MultiMonitorManager::AddRemoveMonitor() {
   MultiMonitorManager* manager = static_cast<MultiMonitorManager*>(
       aura::Env::GetInstance()->monitor_manager());
   manager->AddRemoveMonitorImpl();
 }
 
 void MultiMonitorManager::CycleMonitor() {
@@ skipping 139 matching lines @@
          iter != monitors_.end(); ++iter)
       new_monitors.push_back(Copy(*iter));
     new_monitors.push_back(Copy(monitors_.front()));
     OnNativeMonitorsChanged(new_monitors);
     STLDeleteContainerPointers(new_monitors.begin(), new_monitors.end());
   }
 }
 
 }  // namespace internal
 }  // namespace ash