Add a UseCounter for legacy fullscreen key event filtering

Source/core/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 2928 matching lines @@
         || (keyCode >= VK_OEM_1 && keyCode <= VK_OEM_PLUS)
         || (keyCode >= VK_MULTIPLY && keyCode <= VK_OEM_8);
 }
 
 bool EventHandler::keyEvent(const PlatformKeyboardEvent& initialKeyEvent)
 {
     RefPtr<FrameView> protector(m_frame->view());
 
     ASSERT(m_frame->document());
     if (FullscreenElementStack* fullscreen = FullscreenElementStack::fromIfExists(*m_frame->document())) {
-        if (fullscreen->webkitIsFullScreen() && !isKeyEventAllowedInFullScreen(fullscreen, initialKeyEvent))
+        if (fullscreen->webkitIsFullScreen() && !isKeyEventAllowedInFullScreen(fullscreen, initialKeyEvent)) {
+            UseCounter::count(*m_frame->document(), UseCounter::KeyEventNotAllowedInFullScreen);
             return false;
+        }
     }
 
     if (initialKeyEvent.windowsVirtualKeyCode() == VK_CAPITAL)
         capsLockStateMayHaveChanged();
 
 #if OS(WIN)
     if (panScrollInProgress()) {
         // If a key is pressed while the panScroll is in progress then we want to stop
         if (initialKeyEvent.type() == PlatformEvent::KeyDown || initialKeyEvent.type() == PlatformEvent::RawKeyDown)
             stopAutoscroll();
@@ skipping 860 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace WebCore