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

win8/BUILD.gn

Index: win8/BUILD.gn
diff --git a/win8/BUILD.gn b/win8/BUILD.gn
index 7b36f33dc4498e04803c87011ff1538a147ade7a..fb43d2da1da88998d8ad3308ddc540cb9a5e0597 100644
--- a/win8/BUILD.gn
+++ b/win8/BUILD.gn
@@ -1,6 +1,31 @@
 # 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.
+
+source_set("metro_viewer_constants") {
+  sources = [
+    "viewer/metro_viewer_constants.cc",
+    "viewer/metro_viewer_constants.h",
+  ]
+}
+
+component("metro_viewer") {
+  sources = [
+    "viewer/metro_viewer_process_host.cc",
+    "viewer/metro_viewer_process_host.h",
+  ]
+
+  defines = [ "METRO_VIEWER_IMPLEMENTATION" ]
+
+  deps = [
+    ":metro_viewer_constants",
+    "//base",
+    "//ipc",
+    "//ui/aura",
+    "//ui/gfx",
+    "//ui/metro_viewer",
+  ]
+}
 
 source_set("test_support_win8") {
   sources = [