chromeos: adds TouchDeviceServer and wires up in mushrome

services/ui/input_devices/BUILD.gn

Index: services/ui/input_devices/BUILD.gn
diff --git a/services/ui/input_devices/BUILD.gn b/services/ui/input_devices/BUILD.gn
index bf7b4f8d7aa277a94e62fbff2b9575d45fed0c8d..78a280ed9d3ef8cdd74cfd97b721d795ab70f8d9 100644
--- a/services/ui/input_devices/BUILD.gn
+++ b/services/ui/input_devices/BUILD.gn
@@ -19,6 +19,13 @@ source_set("input_devices") {
   public_deps = [
     "//services/ui/public/interfaces/input_devices",
   ]
+
+  if (is_chromeos) {
+    sources += [
+      "touch_device_server.cc",
+      "touch_device_server.h",
+    ]
+  }
 }
 
 test("input_device_unittests") {