[Media Router] Conditionally enable mDNS on Windows.

chrome/browser/media/android/router/media_router_android.h

Index: chrome/browser/media/android/router/media_router_android.h
diff --git a/chrome/browser/media/android/router/media_router_android.h b/chrome/browser/media/android/router/media_router_android.h
index 21d5086ced9891d980441ec00023d03f2dea40c0..33f964e7c4ae09ebf1ca70568d995801880b7143 100644
--- a/chrome/browser/media/android/router/media_router_android.h
+++ b/chrome/browser/media/android/router/media_router_android.h
@@ -65,6 +65,8 @@ class MediaRouterAndroid : public MediaRouterBase {
       const SendRouteMessageCallback& callback) override;
   void AddIssue(const Issue& issue) override;
   void ClearIssue(const Issue::Id& issue_id) override;
+  bool should_enable_mdns_discovery() const override;
+  void EnsureMdnsDiscoveryEnabled() override;
 
   // The methods called by the Java counterpart.