[webnfc] Introduce NFC mojo service.

device/nfc/BUILD.gn

Index: device/nfc/BUILD.gn
diff --git a/device/nfc/BUILD.gn b/device/nfc/BUILD.gn
index 340c9246df0d0761f48f0c0e258c7e10975e1a95..5932bf6529ed66f02cfb560fddc3d20f020a3c4d 100644
--- a/device/nfc/BUILD.gn
+++ b/device/nfc/BUILD.gn
@@ -2,6 +2,9 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/features.gni")
+import("//mojo/public/tools/bindings/mojom.gni")
+
 static_library("nfc") {
   sources = [
     "nfc_adapter.cc",
@@ -40,3 +43,9 @@ static_library("nfc") {
     ]
   }
 }
+
+mojom("mojo_bindings") {
+  sources = [
+    "nfc.mojom",
+  ]
+}