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

ui/views/event_monitor.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_H_
 #define UI_VIEWS_EVENT_MONITOR_H_
 
+#include "base/memory/scoped_ptr.h"
 #include "ui/gfx/geometry/point.h"
+#include "ui/gfx/native_widget_types.h"
 #include "ui/views/views_export.h"
 
 namespace ui {
 class EventHandler;
 }
 
 namespace views {
 
-// RAII-style class that forwards events posted to the application to
-// |event_handler| before they are dispatched.
+// RAII-style class that forwards events to |event_handler| before they are
+// dispatched.
 class VIEWS_EXPORT EventMonitor {
  public:
   virtual ~EventMonitor() {}
 
-  static EventMonitor* Create(ui::EventHandler* event_handler);
+  // Create an instance for monitoring application events.
+  // Events will be forwarded to |event_handler| before they are dispatched to
+  // the application.
+  static scoped_ptr<EventMonitor> CreateApplicationMonitor(
+      ui::EventHandler* event_handler);
+
+  // Create an instance for monitoring events on a specific window.
+  // Events will be forwarded to |event_handler| before they are dispatched to
+  // |target_window|.
+  // The EventMonitor instance must be destroyed before |target_window|.
+  static scoped_ptr<EventMonitor> CreateWindowMonitor(
+      ui::EventHandler* event_handler,
+      gfx::NativeWindow target_window);
 
   // Returns the last mouse location seen in a mouse event in screen
   // coordinates.
   static gfx::Point GetLastMouseLocation();
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_EVENT_MONITOR_H_