Add ink drop ripple (but no highlight) to comboboxes in harmony.

ui/views/controls/prefix_delegate.h

 // Copyright 2013 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_PREFIX_DELEGATE_H_
 #define UI_VIEWS_CONTROLS_PREFIX_DELEGATE_H_
 
 #include "ui/views/view.h"
+#include "ui/views/views_export.h"
 
 namespace views {
 
 // An interface used to expose lists of items for selection by text input.
-class VIEWS_EXPORT PrefixDelegate : public View {
+class VIEWS_EXPORT PrefixDelegate {
  public:
   // Returns the total number of selectable items.
   virtual int GetRowCount() = 0;
 
   // Returns the row of the currently selected item, or -1 if no item is
   // selected.
   virtual int GetSelectedRow() = 0;
 
   // Sets the selection to the specified row.
   virtual void SetSelectedRow(int row) = 0;
 
   // Returns the item at the specified row.
   virtual base::string16 GetTextForRow(int row) = 0;
-
- protected:
-  ~PrefixDelegate() override {}
 };
 
 } // namespace views
 
 #endif // UI_VIEWS_CONTROLS_PREFIX_DELEGATE_H_