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

win8/metro_driver/BUILD.gn

Index: win8/metro_driver/BUILD.gn
diff --git a/win8/metro_driver/BUILD.gn b/win8/metro_driver/BUILD.gn
index fc66690123428c7e6f7d4b1a44c903f56137479f..68c9a90fc1731e31fffe267858669d24e8c0032b 100644
--- a/win8/metro_driver/BUILD.gn
+++ b/win8/metro_driver/BUILD.gn
@@ -10,6 +10,9 @@
   sources = [
     "display_properties.cc",
     "display_properties.h",
+    "metro_driver.cc",
+    "metro_driver.h",
+    "metro_driver_win7.cc",
     "stdafx.h",
     "winrt_utils.cc",
     "winrt_utils.h",
@@ -33,12 +36,17 @@
 
   if (use_aura) {
     sources += [
+      "chrome_app_view_ash.cc",
+      "chrome_app_view_ash.h",
       "direct3d_helper.cc",
       "direct3d_helper.h",
+      "file_picker_ash.cc",
+      "file_picker_ash.h",
     ]
 
     deps += [
       "//ui/events:gesture_detection",
+      "//win8:metro_viewer_constants",
       "//win8/metro_driver/ime",
     ]
   } else {
@@ -49,6 +57,8 @@
       "chrome_url_launch_handler.h",
       "devices_handler.cc",
       "devices_handler.h",
+      "file_picker.cc",
+      "file_picker.h",
       "metro_dialog_box.cc",
       "metro_dialog_box.h",
       "print_document_source.cc",