Rename FeatureObserver to UseCounter to make clear that all it stores are usage counts.

Source/WebCore/page/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * 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.
@@ skipping 1157 matching lines @@
 #endif
 
     Node* node = event.targetNode();
     RenderObject* renderer = node ? node->renderer() : 0;
     RenderStyle* style = renderer ? renderer->style() : 0;
     bool horizontalText = !style || style->isHorizontalWritingMode();
     const Cursor& iBeam = horizontalText ? iBeamCursor() : verticalTextCursor();
 
 #if ENABLE(CURSOR_VISIBILITY)
     if (style && style->cursorVisibility() == CursorVisibilityAutoHide) {
-        FeatureObserver::observe(m_frame->document(), FeatureObserver::CursorVisibility);
+        UseCounter::observe(m_frame->document(), UseCounter::CursorVisibility);
         startAutoHideCursorTimer();
     } else
         cancelAutoHideCursorTimer();
 #endif
 
     // During selection, use an I-beam no matter what we're over.
     // If a drag may be starting or we're capturing mouse events for a particular node, don't treat this as a selection.
     if (m_mousePressed && m_mouseDownMayStartSelect
         && !m_mouseDownMayStartDrag
         && m_frame->selection()->isCaretOrRange() && !m_capturingMouseEventsNode)
@@ skipping 2811 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(DARWIN)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace WebCore