[Media Router] Conditionally enable mDNS on Windows.

chrome/browser/media/router/media_router_metrics.h

 // 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.
 
 #ifndef CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_METRICS_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_METRICS_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/time/time.h"
 
@@ skipping 58 matching lines @@
   DETACH_ROUTE = 5,
   START_OBSERVING_MEDIA_SINKS = 6,
   STOP_OBSERVING_MEDIA_SINKS = 7,
   START_OBSERVING_MEDIA_ROUTES = 8,
   STOP_OBSERVING_MEDIA_ROUTES = 9,
   LISTEN_FOR_ROUTE_MESSAGES = 10,
   STOP_LISTENING_FOR_ROUTE_MESSAGES = 11,
   CONNECTION_ERROR = 12,
   REGISTER_MEDIA_ROUTE_PROVIDER = 13,
   CONNECT_ROUTE_BY_ROUTE_ID = 14,
+  ENABLE_MDNS_DISCOVERY = 15,
 
   // NOTE: Add entries only immediately above this line.
-  TOTAL_COUNT = 15
+  TOTAL_COUNT = 16
 };
 
 // The install status of the Media Router component extension.
 enum class MediaRouteProviderVersion {
   // Installed but version is invalid or cannot be determined.
   UNKNOWN = 0,
   // Installed and the extension version matches the browser version.
   SAME_VERSION_AS_CHROME = 1,
   // Installed and the extension version is one version behind the browser
   // version.
@@ skipping 60 matching lines @@
   // Returns the version status of the Media Router component extension.
   static MediaRouteProviderVersion GetMediaRouteProviderVersion(
       const base::Version& extension_version,
       const base::Version& browser_version);
 #endif  // !defined(OS_ANDROID)
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_MEDIA_ROUTER_METRICS_H_