Implemented smooth scrolling using xinput2 in X11.

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.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/views/widget/desktop_aura/desktop_window_tree_host_x11.h"
 
 #include <X11/extensions/shape.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xregion.h>
@@ skipping 1644 matching lines @@
   switch (xev->type) {
     case EnterNotify:
     case LeaveNotify: {
       // Ignore EventNotify and LeaveNotify events from children of |xwindow_|.
       // NativeViewGLSurfaceGLX adds a child to |xwindow_|.
       // TODO(pkotwicz|tdanderson): Figure out whether the suppression is
       // necessary. crbug.com/385716
       if (xev->xcrossing.detail == NotifyInferior)
         break;
 
+      // Clear stored scroll data
+      ui::DeviceDataManagerX11::GetInstance()->InvalidateScrollClasses();
+

[sadrul, 2014/12/22 17:11:12]

It looks like this is something that will need to happen in WindowTreeHostX11 as
well if we were to use this on ChromeOS?

       ui::MouseEvent mouse_event(xev);
       DispatchMouseEvent(&mouse_event);
       break;
     }
     case Expose: {
       gfx::Rect damage_rect(xev->xexpose.x, xev->xexpose.y,
                             xev->xexpose.width, xev->xexpose.height);
       compositor()->ScheduleRedrawRect(damage_rect);
       break;
     }
@@ skipping 268 matching lines @@
   if (linux_ui) {
     ui::NativeTheme* native_theme = linux_ui->GetNativeTheme(window);
     if (native_theme)
       return native_theme;
   }
 
   return ui::NativeTheme::instance();
 }
 
 }  // namespace views