Pass origin to StartObservingMediaSinks.

chrome/browser/media/router/media_source_helper.cc

Index: chrome/browser/media/router/media_source_helper.cc
diff --git a/chrome/browser/media/router/media_source_helper.cc b/chrome/browser/media/router/media_source_helper.cc
index 9cf7620fe58bc83fab8aab13a3dcf98356488cba..570df55dd3a750705eecd260e46c13d30645585b 100644
--- a/chrome/browser/media/router/media_source_helper.cc
+++ b/chrome/browser/media/router/media_source_helper.cc
@@ -7,6 +7,7 @@
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "chrome/browser/media/router/media_source.h"
+#include "chrome/common/url_constants.h"
 #include "url/gurl.h"
 
 namespace media_router {
@@ -22,15 +23,24 @@ MediaSource MediaSourceForTab(int tab_id) {
 }
 
 MediaSource MediaSourceForDesktop() {
-  return MediaSource(std::string(kDesktopMediaUrn));
+  MediaSource source(kDesktopMediaUrn);
+  source.set_origin(chrome::kChromeUIMediaRouterURL);
+  return source;
+}
+
+GURL OriginForDesktop() {
+  return GURL(std::string(chrome::kChromeUIMediaRouterURL));
 }
 
 MediaSource MediaSourceForCastApp(const std::string& app_id) {
   return MediaSource(kCastUrnPrefix + app_id);
 }
 
-MediaSource MediaSourceForPresentationUrl(const std::string& presentation_url) {
-  return MediaSource(presentation_url);
+MediaSource MediaSourceForPresentationUrl(const std::string& presentation_url,
+                                          const std::string& origin) {
+  MediaSource source(presentation_url);
+  source.set_origin(origin);
+  return source;
 }
 
 bool IsDesktopMirroringMediaSource(const MediaSource& source) {