Extract a minimal subset of WebDialogUI/WebDialogDelegate from src/chrome -> src/ui/web_dialogs

ui/web_dialogs/web_dialogs_export.h

Index: ui/web_dialogs/web_dialogs_export.h
===================================================================
--- ui/web_dialogs/web_dialogs_export.h	(revision 0)
+++ ui/web_dialogs/web_dialogs_export.h	(revision 0)
@@ -0,0 +1,29 @@
+// Copyright (c) 2011 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_WEB_DIALOGS_WEB_DIALOGS_EXPORT_H_
+#define UI_WEB_DIALOGS_WEB_DIALOGS_EXPORT_H_
+#pragma once
+
+// Defines WEB_DIALOGS_EXPORT so that functionality implemented
+// by the web dialogs module can be exported to consumers.
+
+#if defined(COMPONENT_BUILD)
+#if defined(WIN32)
+
+#if defined(WEB_DIALOGS_IMPLEMENTATION)
+#define WEB_DIALOGS_EXPORT __declspec(dllexport)
+#else
+#define WEB_DIALOGS_EXPORT __declspec(dllimport)
+#endif  // defined(WEB_DIALOGS_IMPLEMENTATION)
+
+#else  // defined(WIN32)
+#define WEB_DIALOGS_EXPORT __attribute__((visibility("default")))
+#endif
+
+#else  // defined(COMPONENT_BUILD)
+#define WEB_DIALOGS_EXPORT
+#endif
+
+#endif  // UI_WEB_DIALOGS_WEB_DIALOGS_EXPORT_H_