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>
@@ skipping 12 matching lines @@
 #include "ui/events/event.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/sequential_id_generator.h"
 #include "ui/gfx/win/window_impl.h"
 #include "ui/views/views_export.h"
 
 namespace gfx {
 class Canvas;
 class ImageSkia;
 class Insets;
-}
+namespace win {
+class DirectManipulationHelper;
+}  // namespace win
+}  // namespace gfx
 
 namespace ui  {
 class ViewProp;
 }
 
 namespace views {
 
 class FullscreenHandler;
 class HWNDMessageHandlerDelegate;
 class WindowsSessionChangeObserver;
@@ skipping 537 matching lines @@
   // glass. Defaults to false.
   bool dwm_transition_desired_;
 
   // Manages observation of Windows Session Change messages.
   scoped_ptr<WindowsSessionChangeObserver> windows_session_change_observer_;
 
   // 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_;

[hans, 2015/08/12 20:24:03]

Another Win/Clang style plugin error:

In file included from ..\..\ui\views\win\hwnd_message_handler.cc:5:
..\..\ui/views/win/hwnd_message_handler.h(594,44) :  error: [chromium-style]
WeakPtrFactory members which refer to their outer class must be the last member
in the outer class definition.
  base::WeakPtrFactory<HWNDMessageHandler> autohide_factory_;
                                           ^

I'll prepare a patch.

 
   // 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_