[Media Router] Implement JoinRoute + update CreateRoute API.

chrome/browser/ui/webui/media_router/media_router_ui.cc

Index: chrome/browser/ui/webui/media_router/media_router_ui.cc
diff --git a/chrome/browser/ui/webui/media_router/media_router_ui.cc b/chrome/browser/ui/webui/media_router/media_router_ui.cc
index 9e6d529de8c5b50026b3a7ac3c90a1a9e15eddfb..752c006433b0d010f45367ce66ddf83da8d170d6 100644
--- a/chrome/browser/ui/webui/media_router/media_router_ui.cc
+++ b/chrome/browser/ui/webui/media_router/media_router_ui.cc
@@ -36,6 +36,8 @@ namespace media_router {
 namespace {
 
 std::string GetHostFromURL(const GURL& gurl) {
+  if (gurl.is_empty())
+    return std::string();
   std::string host = gurl.host();
   if (base::StartsWithASCII(host, "www.", false))
     host = host.substr(4);
@@ -295,6 +297,7 @@ void MediaRouterUI::OnRouteResponseReceived(scoped_ptr<MediaRoute> route,
 bool MediaRouterUI::DoCreateRoute(const MediaSink::Id& sink_id,
                                   MediaCastMode cast_mode) {
   DCHECK(query_result_manager_.get());
+  DCHECK(initiator_);
 
   // Note that there is a rarely-encountered bug, where the MediaCastMode to
   // MediaSource mapping could have been updated, between when the user
@@ -310,10 +313,27 @@ bool MediaRouterUI::DoCreateRoute(const MediaSink::Id& sink_id,
 
   has_pending_route_request_ = true;
   requesting_route_for_default_source_ = cast_mode == MediaCastMode::DEFAULT;
-  router_->CreateRoute(source.id(), sink_id,
+  GURL origin;
+  // TODO(imcheng): What is the origin if not creating route in DEFAULT mode?
+  if (requesting_route_for_default_source_) {
+    origin = frame_url_.GetOrigin();
+  } else {
+    // Requesting route for mirroring. Use a placeholder URL as origin.
+    origin = GURL(chrome::kChromeUIMediaRouterURL);
+  }
+  DCHECK(origin.is_valid());
+
+  DVLOG(1) << "DoCreateRoute: origin: " << origin;
+
+  router_->CreateRoute(source.id(), sink_id, origin,
+                       SessionTabHelper::IdForTab(initiator_),
                        base::Bind(&MediaRouterUI::OnRouteResponseReceived,
                                   weak_factory_.GetWeakPtr()));
   return true;
 }
 
+std::string MediaRouterUI::GetFrameURLHost() const {
+  return GetHostFromURL(frame_url_);
+}
+
 }  // namespace media_router