Add coalesced KeyDown handling for arrow key scrolling.

third_party/WebKit/Source/web/WebFrameWidgetImpl.cpp

 /*
  * Copyright (C) 2014 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 1164 matching lines @@
     return WebInputEventResult::NotHandled;
 
   switch (event.type) {
     case WebInputEvent::Char:
       if (event.windowsKeyCode == VKEY_SPACE) {
         int keyCode = ((event.modifiers & WebInputEvent::ShiftKey) ? VKEY_PRIOR
                                                                    : VKEY_NEXT);
         return scrollViewWithKeyboard(keyCode, event.modifiers);
       }
       break;
+    case WebInputEvent::KeyDown:
     case WebInputEvent::RawKeyDown:
       if (event.modifiers == WebInputEvent::ControlKey) {
         switch (event.windowsKeyCode) {
 #if !OS(MACOSX)
           case 'A':
             WebFrame::fromFrame(focusedCoreFrame())
                 ->toWebLocalFrame()
                 ->executeCommand(WebString::fromUTF8("SelectAll"));
             return WebInputEventResult::HandledSystem;
           case VKEY_INSERT:
@@ skipping 326 matching lines @@
   return flags;
 }
 
 LocalFrame* WebFrameWidgetImpl::focusedLocalFrameAvailableForIme() const {
   if (!m_imeAcceptEvents)
     return nullptr;
   return focusedLocalFrameInWidget();
 }
 
 }  // namespace blink