Enable smooth scrolling on mac

base/mac/scoped_smooth_scrolling_disabler_mac.h

Index: base/mac/scoped_smooth_scrolling_disabler_mac.h
diff --git a/base/mac/scoped_smooth_scrolling_disabler_mac.h b/base/mac/scoped_smooth_scrolling_disabler_mac.h
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+++ b/base/mac/scoped_smooth_scrolling_disabler_mac.h
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+// Copyright (c) 2011 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 BASE_MAC_SCOPED_SMOOTH_SCROLLING_DISABLER_MAC
+#define BASE_MAC_SCOPED_SMOOTH_SCROLLING_DISABLER_MAC
+#pragma once
+
+namespace base {
+
+// A RAII class that disables smooth scrolling. This only has an effect if
+// it's done in the same process as the renderer, i.e. in-process tests.
+class ScopedSmoothScrollingDisabler {
+  public:
+    ScopedSmoothScrollingDisabler(bool actually_disable = true);
+    ~ScopedSmoothScrollingDisabler();
+};
+
+}  // namespace base
+
+#endif  // BASE_MAC_SCOPED_SMOOTH_SCROLLING_DISABLER_MAC