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

win8/viewer/metro_viewer_constants.h

+// Copyright 2013 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 WIN8_VIEWER_METRO_VIEWER_CONSTANTS_H_
+#define WIN8_VIEWER_METRO_VIEWER_CONSTANTS_H_
+
+namespace win8 {
+
+// The name of the IPC channel between the browser process and the metro viewer
+// process.
+extern const char kMetroViewerIPCChannelName[];
+
+// Tells the viewer process to simply connect back without needing to launch a
+// browser process itself.
+extern const wchar_t kMetroViewerConnectVerb[];
+
+}  // namespace win8
+
+#endif  // WIN8_VIEWER_METRO_VIEWER_CONSTANTS_H_