MacViews: Implement event monitoring for a specific window (Reland)

ui/views/event_monitor_mac.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 UI_VIEWS_EVENT_MONITOR_MAC_H_
 #define UI_VIEWS_EVENT_MONITOR_MAC_H_
 
 #include "base/macros.h"
+#include "ui/gfx/native_widget_types.h"
 #include "ui/views/event_monitor.h"
 
-#import <Cocoa/Cocoa.h>
-
 namespace views {
 
 class EventMonitorMac : public EventMonitor {
  public:
-  explicit EventMonitorMac(ui::EventHandler* event_handler);
+  EventMonitorMac(ui::EventHandler* event_handler,
+                  gfx::NativeWindow target_window);
   virtual ~EventMonitorMac();
 
  private:
   id monitor_;
 
   DISALLOW_COPY_AND_ASSIGN(EventMonitorMac);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_EVENT_MONITOR_MAC_H_