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

ui/views/controls/tree/tree_view.h

Index: ui/views/controls/tree/tree_view.h
diff --git a/ui/views/controls/tree/tree_view.h b/ui/views/controls/tree/tree_view.h
index bb56735c67a82908ee848df656e525aad640729f..645ceebf6a2ef9add5f6925211fa09c99716dbe5 100644
--- a/ui/views/controls/tree/tree_view.h
+++ b/ui/views/controls/tree/tree_view.h
@@ -35,7 +35,8 @@ class PrefixSelector;
 // Note on implementation. This implementation doesn't scale well. In particular
 // it does not store any row information, but instead calculates it as
 // necessary. But it's more than adequate for current uses.
-class VIEWS_EXPORT TreeView : public ui::TreeModelObserver,
+class VIEWS_EXPORT TreeView : public View,
+                              public ui::TreeModelObserver,
                               public TextfieldController,
                               public FocusChangeListener,
                               public PrefixDelegate {