Improve scroll performance on Windows 10 with high precision touchpads.

ui/views/win/hwnd_message_handler.h

 // 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.
 
 #ifndef UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_
 #define UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_
 
 #include <windows.h>
 
 #include <set>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/strings/string16.h"
 #include "base/win/scoped_gdi_object.h"
 #include "base/win/win_util.h"
 #include "ui/accessibility/ax_enums.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/base/win/window_event_target.h"
 #include "ui/events/event.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/sequential_id_generator.h"
+#include "ui/gfx/win/direct_manipulation.h"

[sky, 2015/08/11 23:45:02]

forward declare the class and include in the .cc.

[ananta, 2015/08/12 00:41:58]

Done.

 #include "ui/gfx/win/window_impl.h"
 #include "ui/views/views_export.h"
 
 namespace gfx {
 class Canvas;
 class ImageSkia;
 class Insets;
 }
 
 namespace ui  {
@@ skipping 550 matching lines @@
 
   // The WeakPtrFactories below must occur last in the class definition so they
   // get destroyed last.
 
   // The factory used to lookup appbar autohide edges.
   base::WeakPtrFactory<HWNDMessageHandler> autohide_factory_;
 
   // The factory used with BEGIN_SAFE_MSG_MAP_EX.
   base::WeakPtrFactory<HWNDMessageHandler> weak_factory_;
 
+  // This class provides functionality to register the legacy window as a
+  // Direct Manipulation consumer. This allows us to support smooth scroll
+  // in Chrome on Windows 10.
+  scoped_ptr<gfx::win::DirectManipulationHelper> direct_manipulation_helper_;
+
   DISALLOW_COPY_AND_ASSIGN(HWNDMessageHandler);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_