Pass origin to StartObservingMediaSinks.

chrome/test/media_router/test_media_sinks_observer.cc

Index: chrome/test/media_router/test_media_sinks_observer.cc
diff --git a/chrome/test/media_router/test_media_sinks_observer.cc b/chrome/test/media_router/test_media_sinks_observer.cc
index c4a9fce51dcfaa7085133f3cc6fea7aac5737497..2148b9de88e3b020c3a71eb0913ab48dcf91940d 100644
--- a/chrome/test/media_router/test_media_sinks_observer.cc
+++ b/chrome/test/media_router/test_media_sinks_observer.cc
@@ -7,6 +7,7 @@
 
 #include "chrome/browser/media/router/media_router.h"
 #include "chrome/test/media_router/test_media_sinks_observer.h"
+#include "url/gurl.h"
 
 namespace media_router {
 
@@ -19,7 +20,11 @@ TestMediaSinksObserver::~TestMediaSinksObserver() {
 }
 
 void TestMediaSinksObserver::OnSinksReceived(
+    const MediaSource& incomingSource,
     const std::vector<MediaSink>& result) {
+  if (!incomingSource.Equals(source())) {
+    return;
+  }
   sink_map.clear();
   for (const MediaSink& sink : result) {
     sink_map.insert(std::make_pair(sink.name(), sink));