Remove views::SingleSplitView as it's presently unused.

ui/views/controls/single_split_view_listener.h

Index: ui/views/controls/single_split_view_listener.h
diff --git a/ui/views/controls/single_split_view_listener.h b/ui/views/controls/single_split_view_listener.h
deleted file mode 100644
index 0d589c9cfb8e11ac1fedb62c7828f840e6cedfe7..0000000000000000000000000000000000000000
--- a/ui/views/controls/single_split_view_listener.h
+++ /dev/null
@@ -1,30 +0,0 @@
-// 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 UI_VIEWS_CONTROLS_SINGLE_SPLIT_VIEW_LISTENER_H_
-#define UI_VIEWS_CONTROLS_SINGLE_SPLIT_VIEW_LISTENER_H_
-
-#include "ui/views/views_export.h"
-
-namespace views {
-
-class SingleSplitView;
-
-// An interface implemented by objects that want to be notified when the
-// splitter moves.
-class VIEWS_EXPORT SingleSplitViewListener {
- public:
-  // Invoked when split handle is moved by the user. |sender|'s divider_offset
-  // is already set to the new value, but Layout has not happened yet.
-  // Returns false if the layout has been handled by the listener, returns
-  // true if |sender| should do it by itself.
-  virtual bool SplitHandleMoved(SingleSplitView* sender) = 0;
-
- protected:
-  virtual ~SingleSplitViewListener() {}
-};
-
-}  // namespace views
-
-#endif  // UI_VIEWS_CONTROLS_SINGLE_SPLIT_VIEW_LISTENER_H_