Revert of Remove remote tree host and some related input and metro_driver code

win8/viewer/metro_viewer_exports.h

Index: win8/viewer/metro_viewer_exports.h
diff --git a/win8/viewer/metro_viewer_exports.h b/win8/viewer/metro_viewer_exports.h
new file mode 100644
index 0000000000000000000000000000000000000000..61ff7d51680dea64d26f2ef59d6d1a295630fa94
--- /dev/null
+++ b/win8/viewer/metro_viewer_exports.h
@@ -0,0 +1,29 @@
+// 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 METRO_VIEWER_METRO_VIEWER_H_
+#define METRO_VIEWER_METRO_VIEWER_H_
+
+#if defined(COMPONENT_BUILD)
+#if defined(WIN32)
+
+#if defined(METRO_VIEWER_IMPLEMENTATION)
+#define METRO_VIEWER_EXPORT __declspec(dllexport)
+#else
+#define METRO_VIEWER_EXPORT __declspec(dllimport)
+#endif  // defined(METRO_VIEWER_IMPLEMENTATION)
+
+#else  // defined(WIN32)
+#if defined(METRO_VIEWER_IMPLEMENTATION)
+#define METRO_VIEWER_EXPORT __attribute__((visibility("default")))
+#else
+#define METRO_VIEWER_EXPORT
+#endif
+#endif
+
+#else  // defined(COMPONENT_BUILD)
+#define METRO_VIEWER_EXPORT
+#endif
+
+#endif  // METRO_VIEWER_METRO_VIEWER_H_