Clean up some remaining obsolete coordinate-space naming.

third_party/WebKit/Source/platform/PlatformMouseEvent.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 71 matching lines @@
     const IntPoint& movementDelta() const { return m_movementDelta; }
 
     MouseButton button() const { return m_button; }
     int clickCount() const { return m_clickCount; }
     bool fromTouch() const { return m_synthesized == FromTouch; }
     SyntheticEventType syntheticEventType() const { return m_synthesized; }
 
 protected:
     WebPointerProperties m_pointerProperties;
 
+    // In local root frame coordinates. (Except possibly if the Widget under
+    // the mouse is a popup, see FIXME in PlatformMouseEventBuilder).
     IntPoint m_position;
+
+    // In screen coordinates.
     IntPoint m_globalPosition;
+
     IntPoint m_movementDelta;
     MouseButton m_button;
     int m_clickCount;
     SyntheticEventType m_synthesized;
 };
 
 } // namespace blink
 
 #endif // PlatformMouseEvent_h