Adding support for sending horizonatal mouse wheel information in Chrome ASH on Windows 8.

ui/aura/remote_root_window_host_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/aura/remote_root_window_host_win.h"
 
 #include <windows.h>
 
 #include <algorithm>
 
@@ skipping 506 matching lines @@
 
 void RemoteWindowTreeHostWin::OnMouseButton(
     const MetroViewerHostMsg_MouseButtonParams& params) {
   gfx::Point location = PointFromNativeEvent(params.x, params.y);
   ui::MouseEvent mouse_event(params.event_type, location, location,
                              static_cast<int>(params.flags),
                              static_cast<int>(params.changed_button));
 
   SetEventFlags(params.flags | key_event_flags());
   if (params.event_type == ui::ET_MOUSEWHEEL) {
-    ui::MouseWheelEvent wheel_event(mouse_event, 0, params.extra);
+    int x_offset = params.is_horizontal_wheel ? params.extra : 0;
+    int y_offset = !params.is_horizontal_wheel ? params.extra : 0;
+    ui::MouseWheelEvent wheel_event(mouse_event, x_offset, y_offset);
     delegate_->OnHostMouseEvent(&wheel_event);
   } else if (params.event_type == ui::ET_MOUSE_PRESSED) {
     // TODO(shrikant): Ideally modify code in event.cc by adding automatic
     // tracking of double clicks in synthetic MouseEvent constructor code.
     // Non-synthetic MouseEvent constructor code does automatically track
     // this. Need to use some caution while modifying synthetic constructor
     // as many tests and other code paths depend on it and apparently
     // specifically depend on non implicit tracking of previous mouse event.
     if (last_mouse_click_event_ &&
         ui::MouseEvent::IsRepeatedClickEvent(mouse_event,
@@ skipping 199 matching lines @@
 }
 
 void RemoteWindowTreeHostWin::SetEventFlags(uint32 flags) {
   if (flags == event_flags_)
     return;
   event_flags_ = flags;
   SetVirtualKeyStates(event_flags_);
 }
 
 }  // namespace aura