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..d5a0696e6cb6c7e706835c466fb2c1fda833d9d3 100644
--- a/chrome/browser/media/router/media_source_helper.cc
+++ b/chrome/browser/media/router/media_source_helper.cc
@@ -16,6 +16,7 @@ namespace media_router {
 const char kTabMediaUrnPrefix[] = "urn:x-org.chromium.media:source:tab";
 const char kDesktopMediaUrn[] = "urn:x-org.chromium.media:source:desktop";
 const char kCastUrnPrefix[] = "urn:x-com.google.cast:application:";
+const char kOrigin[] = "";
 
 MediaSource MediaSourceForTab(int tab_id) {
   return MediaSource(base::StringPrintf("%s:%d", kTabMediaUrnPrefix, tab_id));
@@ -25,6 +26,10 @@ MediaSource MediaSourceForDesktop() {
   return MediaSource(std::string(kDesktopMediaUrn));
 }
 
+GURL OriginForDesktop() {

[mark a. foltz, 2016/02/17 21:50:51]

If we need an origin for tab and desktop casting, it would probably be the media
router WebUI, chrome://media-router

https://code.google.com/p/chromium/codesearch#chromium/src/chrome/common/url_...

This is what we pass to CreateRoute()

[matt.boetger, 2016/02/18 00:50:33]

Done.

+  return GURL(std::string(kOrigin));
+}
+
 MediaSource MediaSourceForCastApp(const std::string& app_id) {
   return MediaSource(kCastUrnPrefix + app_id);
 }