Implement Sebastien's overlay scrollbars for native UI (Views).

ui/views/controls/scroll_view.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/controls/scroll_view.h"
 
 #include "base/feature_list.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "ui/events/event.h"
@@ skipping 438 matching lines @@
 
   if (vert_sb_->visible())
     processed = vert_sb_->OnMouseWheel(e);
 
   if (horiz_sb_->visible())
     processed = horiz_sb_->OnMouseWheel(e) || processed;
 
   return processed;
 }
 
-void ScrollView::OnMouseEntered(const ui::MouseEvent& event) {
-  if (horiz_sb_)
-    horiz_sb_->OnMouseEnteredScrollView(event);
-  if (vert_sb_)
-    vert_sb_->OnMouseEnteredScrollView(event);
-}
-
-void ScrollView::OnMouseExited(const ui::MouseEvent& event) {
-  if (horiz_sb_)
-    horiz_sb_->OnMouseExitedScrollView(event);
-  if (vert_sb_)
-    vert_sb_->OnMouseExitedScrollView(event);
-}
-
 void ScrollView::OnScrollEvent(ui::ScrollEvent* event) {
 #if defined(OS_MACOSX)
   // TODO(tapted): Send |event| to a cc::InputHandler. For now, there's nothing
   // to do because Widget::OnScrollEvent() will automatically process an
   // unhandled ScrollEvent as a MouseWheelEvent.
 #endif
 }
 
 void ScrollView::OnGestureEvent(ui::GestureEvent* event) {
   // If the event happened on one of the scrollbars, then those events are
@@ skipping 302 matching lines @@
 
 VariableRowHeightScrollHelper::RowInfo
     FixedRowHeightScrollHelper::GetRowInfo(int y) {
   if (y < top_margin_)
     return RowInfo(0, top_margin_);
   return RowInfo((y - top_margin_) / row_height_ * row_height_ + top_margin_,
                  row_height_);
 }
 
 }  // namespace views