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

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 26362e10a694143a51d0fba9b523a486a1fd99af..40e66aaec8b0b446b3329ee2a9477f45972c15fc 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
@@ -360,6 +360,16 @@ Polymer({
     },
 
     /**
+     * ID of the sink waiting for the current route to it to be closed so a new
+     * one can be started, or the empty string when no such sink is waiting.
+     * @private {string}
+     */
+    sinkIdAwaitingNewRoute_: {

[apacible, 2016/05/25 00:56:34]

Could we generalize |currentLaunchingSinkId_| for this?

[btolsch, 2016/05/25 20:53:44]

Done. I think we still need a boolean indicating which use it currently has to
avoid extra create-route events from rebuildRouteMaps_(), but the sink spinner
would work automatically while we're waiting for the route to connect.

+      type: String,
+      value: '',
+    },
+
+    /**
      * Max height for the sink list.
      * @private {number}
      */
@@ -614,6 +624,24 @@ Polymer({
   },
 
   /**
+   * @param {!media_router.Route} route
+   * @return {number} Bitmask of cast modes available for the sink of |route|.
+   *     There will be no more than 1 bit set if the user has selected a
+   *     specific cast mode.
+   */
+  computeAvailableCastModesForRoute_: function(route) {
+    if (route && route.sinkId && this.sinkMap_[route.sinkId]) {
+      var sinkCastModes = this.sinkMap_[route.sinkId].castModes;
+      if (this.shownCastModeValue_ == media_router.CastModeType.AUTO) {
+        return sinkCastModes;
+      } else {
+        return this.shownCastModeValue_ & sinkCastModes;
+      }
+    }
+    return 0;
+  },
+
+  /**
    * If |allSinks| supports only a single cast mode, returns that cast mode.
    * Otherwise, returns AUTO_MODE. Only called if |userHasSelectedCastMode_| is
    * |false|.
@@ -711,7 +739,7 @@ Polymer({
       case media_router.MediaRouterView.ISSUE:
         return this.i18n('issueHeaderText');
       case media_router.MediaRouterView.ROUTE_DETAILS:
-        return this.currentRoute_ ?
+        return this.currentRoute_ && this.sinkMap_[this.currentRoute_.sinkId] ?
             this.sinkMap_[this.currentRoute_.sinkId].name : '';
       case media_router.MediaRouterView.SINK_LIST:
       case media_router.MediaRouterView.FILTER:
@@ -1571,6 +1599,25 @@ Polymer({
   },
 
   /**
+   * Handles a cast-new-media-click event. Closes the currently displayed local
+   * route and shows the sink list. When the current route has been successfully
+   * removed from the route map, the container will launch a new route for the
+   * same sink.
+   *
+   * @param {!Event} event The event object.
+   * Parameters in |event|.detail:
+   *   route - route to close.
+   * @private
+   */
+  onCastNewMediaClick_: function(event) {

[apacible, 2016/05/25 00:56:34]

We should keep track if this is the first user action. There are some examples
in this file, e.g. in onCloseRouteClick_().

[btolsch, 2016/05/25 20:53:44]

Done. I reused START_LOCAL for this, but let me know if you think it should be a
new event, possibly JOIN_ROUTE or CAST_TO_ROUTE.

[apacible, 2016/05/25 22:37:01]

I'd prefer a new event, since it may be useful to differentiate between the two
scenarios.

[btolsch, 2016/05/26 00:31:12]

Done.  Used CAST_TO_ROUTE.

+    /** @type {{route: !media_router.Route}} */
+    var detail = event.detail;
+    this.sinkIdAwaitingNewRoute_ = detail.route.sinkId;

[apacible, 2016/05/25 00:56:34]

UX question: Do we expect the dialog to close after 3s of the new route
resolving, similar to if we're casting on an otherwise inactive sink?

[btolsch, 2016/05/25 20:53:44]

That's what I would expect.  Do you think it should be kept open
unconditionally?

[apacible, 2016/05/25 22:37:01]

No, that sg.

+    this.fire('close-route-for-new-media', detail);
+    this.showSinkList_();
+  },
+
+  /**
    * Handles a close-route-click event. Shows the sink list and starts a timer
    * to close the dialog if there is no click within three seconds.
    *
@@ -1936,6 +1983,15 @@ Polymer({
 
     this.sinkToRouteMap_ = tempSinkToRouteMap;
     this.rebuildSinksToShow_();
+
+    // A sink was waiting for its route to be closed and removed from the route
+    // map so a new route to it can be started.
+    if (this.sinkIdAwaitingNewRoute_ != '' &&
+        !(this.sinkIdAwaitingNewRoute_ in this.sinkToRouteMap_) &&
+        this.sinkIdAwaitingNewRoute_ in this.sinkMap_) {
+      this.showOrCreateRoute_(this.sinkMap_[this.sinkIdAwaitingNewRoute_]);
+      this.sinkIdAwaitingNewRoute_ = '';
+    }
   },
 
   /**