[Media Router] Handle route swapping in the WebUI.

chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js

Index: chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js
diff --git a/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js b/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js
index 0db284868dbffae2fdf5c0443c083c0db03cf89d..e69ca14af9a63d3c4a8ef3ba796f91ba9915a65b 100644
--- a/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js
+++ b/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.js
@@ -889,10 +889,18 @@ Polymer({
     // switch back to the SINK_PICKER view if the user is currently in the
     // ROUTE_DETAILS view.
     if (!this.currentRoute_ || !this.routeMap_[this.currentRoute_.id]) {
-      if (this.currentView_ == media_router.MediaRouterView.ROUTE_DETAILS)
-        this.showSinkList_();
-      else
+      if (this.currentView_ == media_router.MediaRouterView.ROUTE_DETAILS) {
+        // We may have an updated route to show for a device.
+        // We swap out |currentRoute_| (and consequently the route-details
+        // controls) to handle this.
+        this.currentRoute_ =
+            tempSinkToRouteMap[this.currentRoute_.sinkId] || null;
+
+        if (!this.currentRoute_)
+          this.showSinkList_();
+      } else {
         this.currentRoute_ = null;
+      }
     }
 
     this.sinkToRouteMap_ = tempSinkToRouteMap;