[Media Router] Conditionally enable mDNS on Windows.

chrome/browser/media/router/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//testing/test.gni")
 
 gypi_values = exec_script("//build/gypi_to_gn.py",
                           [ rebase_path("media_router.gypi") ],
@@ skipping 16 matching lines @@
   if (!is_android) {
     deps += [
       ":mojo_bindings",
       "//extensions/browser",
       "//mojo/public/cpp/bindings",
     ]
     sources += rebase_path(gypi_values.media_router_non_android_sources,
                            ".",
                            "//chrome/browser/media/router")
   }
+  if (is_win) {
+    sources += rebase_path(gypi_values.media_router_win_sources)
+  }
 }
 
 mojom("mojo_bindings") {
   sources = [
     "media_router.mojom",
   ]
 }
 
 source_set("test_support") {
   testonly = true
   deps = [
     # TODO(crbug.com/596999): Move non-Android code to mojo/
     ":mojo_bindings",
     ":router",
     "//chrome/test:test_support",
     "//testing/gmock",
   ]
   sources = rebase_path(gypi_values.media_router_test_support_sources,
                         ".",
                         "//chrome/browser/media/router")
   if (!is_android) {
     deps += [ "//extensions/common" ]
     sources +=
         rebase_path(gypi_values.media_router_non_android_test_support_sources,
                     ".",
                     "//chrome/browser/media/router")
   }
 }