[Media Router] Allow casting new media to sink with existing route.

chrome/browser/resources/media_router/media_router.js

Index: chrome/browser/resources/media_router/media_router.js
diff --git a/chrome/browser/resources/media_router/media_router.js b/chrome/browser/resources/media_router/media_router.js
index 834f9effc655bd84f1fc3004b5d1c4caf8872abb..f5883c21be309ae777b650bce5643f96eff22695 100644
--- a/chrome/browser/resources/media_router/media_router.js
+++ b/chrome/browser/resources/media_router/media_router.js
@@ -37,6 +37,8 @@ cr.define('media_router', function() {
     container.addEventListener('cast-mode-selected', onCastModeSelected);
     container.addEventListener('close-dialog', onCloseDialog);
     container.addEventListener('close-route-click', onCloseRouteClick);
+    container.addEventListener('close-route-for-new-media',
+                               onCloseRouteForNewMedia);
     container.addEventListener('create-route', onCreateRoute);
     container.addEventListener('issue-action-click', onIssueActionClick);
     container.addEventListener('navigate-sink-list-to-details',
@@ -221,6 +223,20 @@ cr.define('media_router', function() {
   }
 
   /**
+   * Stops a route.
+   * Called when the user requests to cast to a sink that already has a route.
+   *
+   * @param {!Event} event
+   * Parameters in |event|.detail:
+   *   route - The route to close.
+   */
+  function onCloseRouteForNewMedia(event) {
+    /** @type {{route: !media_router.Route}} */
+    var detail = event.detail;
+    media_router.browserApi.closeRoute(detail.route);
+  }
+
+  /**
    * Starts casting to an existing route.
    * Called when the user requests to start casting to a media route.
    *