Replace ButtonDropDown menu implementation (Menu2) with MenuItemView.

views/controls/menu/menu_model_adapter_unittest.cc

Index: views/controls/menu/menu_model_adapter_unittest.cc
diff --git a/views/controls/menu/menu_model_adapter_unittest.cc b/views/controls/menu/menu_model_adapter_unittest.cc
index dba68c80f1bed0e481a5e1394caa42cb6b89830e..035ec165a89224e7fa32a544a8801a45ab30604d 100644
--- a/views/controls/menu/menu_model_adapter_unittest.cc
+++ b/views/controls/menu/menu_model_adapter_unittest.cc
@@ -293,6 +293,11 @@ TEST_F(MenuModelAdapterTest, BasicTest) {
     EXPECT_EQ(i + kFirstItemIndex, submodel->last_activation());
     submodel->set_last_activation(-1);
   }
+
+  // Check that selecting the root item is safe.  The MenuModel does
+  // not care about the root so MenuModelAdapter should do nothing
+  // (not hit the NOTREACHED check) when the root is selected.
+  static_cast<views::MenuDelegate*>(&delegate)->SelectionChanged(menu.get());
 }
 
 }  // namespace views