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

chrome/browser/media/router/media_source.h

Index: chrome/browser/media/router/media_source.h
diff --git a/chrome/browser/media/router/media_source.h b/chrome/browser/media/router/media_source.h
index 288cb27b7791bdfdca6d04ce345df9aeb64ce604..9a28f8d0c7c2df6b74fd805180c1f981151d69a5 100644
--- a/chrome/browser/media/router/media_source.h
+++ b/chrome/browser/media/router/media_source.h
@@ -20,17 +20,13 @@ class MediaSource {
   using Id = std::string;
 
   explicit MediaSource(const MediaSource::Id& id);
-  MediaSource();
   ~MediaSource();
 
   // Gets the ID of the media source.
   MediaSource::Id id() const;
 
   // Returns true if two MediaSource objects use the same media ID.
-  bool Equals(const MediaSource& other) const;
-
-  // Returns true if a MediaSource is empty or uninitialized.
-  bool Empty() const;
+  bool operator==(const MediaSource& other) const;
 
   // Used for logging.
   std::string ToString() const;
@@ -42,6 +38,14 @@ class MediaSource {
     }
   };
 
+  // For storing in sets and in maps as keys.
+  struct Compare {
+    bool operator()(const MediaSource& source1,
+                    const MediaSource& source2) const {
+      return source1.id() < source2.id();
+    }
+  };
+
  private:
   MediaSource::Id id_;
 };