Add coalesced KeyDown handling for arrow key scrolling.

third_party/WebKit/Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 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 1653 matching lines @@
           element.unwrap<Element>());
   }
 }
 
 bool WebViewImpl::keyEventDefault(const WebKeyboardEvent& event) {
   LocalFrame* frame = toLocalFrame(focusedCoreFrame());
   if (!frame)
     return false;
 
   switch (event.type) {
     case WebInputEvent::Char:

[aelias_OOO_until_Jul13, 2016/10/19 17:55:09]

Note that although Android does not send Char event either, surprisingly,
spacebar scrolling still works.  The reason is that spacebar scrolling is
handled by KeyboardEventManager::defaultSpaceEventHandler.  That gets dibs on
the event first, so as far as I can tell this spacebar switch clause has
actually been no-op for a long time.

       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':
             focusedFrame()->executeCommand(WebString::fromUTF8("SelectAll"));
             return true;
           case VKEY_INSERT:
           case 'C':
             focusedFrame()->executeCommand(WebString::fromUTF8("Copy"));
@@ skipping 3051 matching lines @@
   if (focusedFrame->localFrameRoot() != mainFrameImpl()->frame())
     return nullptr;
   return focusedFrame;
 }
 
 LocalFrame* WebViewImpl::focusedLocalFrameAvailableForIme() const {
   return m_imeAcceptEvents ? focusedLocalFrameInWidget() : nullptr;
 }
 
 }  // namespace blink