Aura needs event translation for Mac

ui/base/events.h

 // Copyright (c) 2011 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_BASE_EVENTS_H_
 #define UI_BASE_EVENTS_H_
 #pragma once
 
 #include "base/event_types.h"
 #include "ui/base/keycodes/keyboard_codes.h"
@@ skipping 62 matching lines @@
 
 // Updates the list of devices for cached properties.
 UI_EXPORT void UpdateDeviceList();
 
 // Get the EventType from a native event.
 UI_EXPORT EventType EventTypeFromNative(const base::NativeEvent& native_event);
 
 // Get the EventFlags from a native event.
 UI_EXPORT int EventFlagsFromNative(const base::NativeEvent& native_event);
 
-// Get the location from a native event.
+// Get the location from a native event.  The coordinate system of the resultant
+// |Point| has the origin at top-left of the "root window".  The nature of
+// this "root window" and how it maps to platform-specific drawing surfaces is
+// defined in ui/aura/root_window.* and ui/aura/root_window_host*.
 UI_EXPORT gfx::Point EventLocationFromNative(
     const base::NativeEvent& native_event);
 
 #if defined(USE_X11)
 // Returns the 'real' button for an event. The button reported in slave events
 // does not take into account any remapping (e.g. using xmodmap), while the
 // button reported in master events do. This is a utility function to always
 // return the mapped button.
 UI_EXPORT int EventButtonFromNative(const base::NativeEvent& native_event);
 #endif
@@ skipping 26 matching lines @@
 UI_EXPORT bool GetScrollOffsets(const base::NativeEvent& native_event,
                                 float* x_offset,
                                 float* y_offset);
 
 // Creates and returns no-op event.
 UI_EXPORT base::NativeEvent CreateNoopEvent();
 
 }  // namespace ui
 
 #endif  // UI_BASE_EVENTS_H_