Add Mojo interfaces for out-of-process proxy resolver.

net/interfaces/BUILD.gn

Index: net/interfaces/BUILD.gn
diff --git a/chrome/browser/metro_utils/BUILD.gn b/net/interfaces/BUILD.gn
similarity index 52%
copy from chrome/browser/metro_utils/BUILD.gn
copy to net/interfaces/BUILD.gn
index 86a28875cc8bb6787a0807467adcbb3072e01ce0..03a07785251e4d2fa222319e0a4cab1d0c4c5f9a 100644
--- a/chrome/browser/metro_utils/BUILD.gn
+++ b/net/interfaces/BUILD.gn
@@ -2,13 +2,11 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("metro_utils") {
-  deps = [
-    "//base",
-    "//chrome/installer/util",
-  ]
+import("//third_party/mojo/src/mojo/public/tools/bindings/mojom.gni")
+
+mojom("interfaces") {
   sources = [
-    "metro_chrome_win.cc",
-    "metro_chrome_win.h",
+    "host_resolver_service.mojom",
+    "proxy_resolver_service.mojom",
   ]
 }