Remove windows/mac/ios specific code from //ui

ui/platform_window/win/win_window_export.h

Index: ui/platform_window/win/win_window_export.h
diff --git a/ui/platform_window/win/win_window_export.h b/ui/platform_window/win/win_window_export.h
deleted file mode 100644
index 69d86d229792d4916ace6fb1094b06dc7efee85c..0000000000000000000000000000000000000000
--- a/ui/platform_window/win/win_window_export.h
+++ /dev/null
@@ -1,30 +0,0 @@
-// Copyright 2014 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_PLATFORM_WINDOW_WIN_WIN_WINDOW_EXPORT_H_
-#define UI_PLATFORM_WINDOW_WIN_WIN_WINDOW_EXPORT_H_
-
-#if defined(COMPONENT_BUILD)
-#if defined(WIN32)
-
-#if defined(WIN_WINDOW_IMPLEMENTATION)
-#define WIN_WINDOW_EXPORT __declspec(dllexport)
-#else
-#define WIN_WINDOW_EXPORT __declspec(dllimport)
-#endif  // defined(WIN_WINDOW_IMPLEMENTATION)
-
-#else  // defined(WIN32)
-#if defined(WIN_WINDOW_IMPLEMENTATION)
-#define WIN_WINDOW_EXPORT __attribute__((visibility("default")))
-#else
-#define WIN_WINDOW_EXPORT
-#endif
-#endif
-
-#else  // defined(COMPONENT_BUILD)
-#define WIN_WINDOW_EXPORT
-#endif
-
-#endif  // UI_PLATFORM_WINDOW_WIN_WIN_WINDOW_EXPORT_H
-