[Presentation API] Add support for multiple URLs in PresentationRequest on Media Router UI side

chrome/browser/media/router/media_sink.h

Index: chrome/browser/media/router/media_sink.h
diff --git a/chrome/browser/media/router/media_sink.h b/chrome/browser/media/router/media_sink.h
index f39e36890178f26d022ab192d93c8afbc8ab7835..b8720a13f20aacfd7a74f8cc8c74c55bef16028f 100644
--- a/chrome/browser/media/router/media_sink.h
+++ b/chrome/browser/media/router/media_sink.h
@@ -44,6 +44,13 @@ class MediaSink {
 
   bool Equals(const MediaSink& other) const;
 
+  // For storing in sets and in maps as keys
+  struct Compare {
+    bool operator()(const MediaSink& sink1, const MediaSink& sink2) const {
+      return sink1.id() < sink2.id();
+    }
+  };
+
  private:
   // Unique identifier for the MediaSink.
   MediaSink::Id sink_id_;