Moving input device hotplug event processing outside of ui/display

ash/BUILD.gn

Index: ash/BUILD.gn
diff --git a/ash/BUILD.gn b/ash/BUILD.gn
index a2ed2df1f271470d8232d05c74bee791311cb1e9..5fad0338e1b66eddcd889daad88ae4bda5df1926 100644
--- a/ash/BUILD.gn
+++ b/ash/BUILD.gn
@@ -107,6 +107,8 @@ component("ash") {
     sources -= [
       "touch/touch_transformer_controller.cc",
       "touch/touch_transformer_controller.h",
+      "touch/touchscreen_util.cc",
+      "touch/touchscreen_util.h",
     ]
   }
 
@@ -321,6 +323,7 @@ test("ash_unittests") {
     sources -= [
       "display/resolution_notification_controller_unittest.cc",
       "touch/touch_transformer_controller_unittest.cc",
+      "touch/touchscreen_util_unittest.cc",
     ]
   }