[MD] Don't use new OTR native-theming when using a custom browser theme.

chrome/browser/ui/views/theme_copying_widget.cc

Index: chrome/browser/ui/views/theme_copying_widget.cc
diff --git a/chrome/browser/ui/views/theme_copying_widget.cc b/chrome/browser/ui/views/theme_copying_widget.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a9e2d191576fbf961c609d6f2c8a8df019bb971a
--- /dev/null
+++ b/chrome/browser/ui/views/theme_copying_widget.cc
@@ -0,0 +1,14 @@
+// Copyright 2016 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.
+
+#include "chrome/browser/ui/views/theme_copying_widget.h"
+
+ThemeCopyingWidget::ThemeCopyingWidget(views::Widget* role_model)
+    : role_model_(role_model) {}
+
+ThemeCopyingWidget::~ThemeCopyingWidget() {}
+
+const ui::NativeTheme* ThemeCopyingWidget::GetNativeTheme() const {
+  return role_model_->GetNativeTheme();
+}