Add chrome side webusb permission UI code

chrome/browser/ui/website_settings/chooser_bubble_delegate.cc

+// Copyright 2015 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/website_settings/chooser_bubble_delegate.h"
+
+#if defined(OS_MACOSX)
+#include "components/bubble/bubble_ui.h"
+#endif
+
+ChooserBubbleDelegate::ChooserBubbleDelegate(Browser* browser)
+    : browser_(browser) {}
+
+ChooserBubbleDelegate::~ChooserBubbleDelegate() {}
+
+std::string ChooserBubbleDelegate::GetName() const {
+  return "ChooserBubble";
+}
+
+// TODO(juncai): Add chooser bubble ui cocoa code for Mac.
+// Please refer to http://crbug.com/492204 for more information.
+#if defined(OS_MACOSX)
+scoped_ptr<BubbleUi> ChooserBubbleDelegate::BuildBubbleUi() {
+  return scoped_ptr<BubbleUi>();
+}
+#endif