[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..31bed7d089db9e4dcfafab3a3271bb6a79daf894 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
@@ -200,6 +200,17 @@ Polymer({
     },
 
     /**
+     * Whether the currently launching sink, whose ID is given by
+     * |currentLaunchingSinkId_|, is waiting for the current route to it to be
+     * closed so a new one can be started.
+     * @private {boolean}
+     */
+    launchingSinkAwaitingRouteClose_: {
+      type: Boolean,
+      value: false,
+    },
+
+    /**
      * Whether the user's mouse is positioned over the dialog.
      * @private {boolean|undefined}
      */
@@ -614,6 +625,24 @@ 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 +740,7 @@ 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] ?

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

Is this relevant to your main changes? I was looking at this earlier:
If there is a |currentRoute_|, the dialog closes, you navigate to another tab
where the cast modes are a mismatch, then open the dialog again, you'll see the
route details but the default "Cast to" header.

It may be better to check allSinks for the existing sink rather than just
sinkMap. If the sink just doesn't exist anymore, we shouldn't show the route.

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

This change doesn't have to be made here, but I thought it was semi-relevant. 
It addresses the scenario you described.

I'm not sure what you mean by "if the sink just doesn't exist anymore."  A sink
can be missing from allSinks just because it doesn't support the available cast
modes, even though MR might still be aware of it.  Are you suggesting that
maybeShowRouteDetailsOnOpen() shouldn't show route details when the sink isn't
present in allSinks?

Lastly, what does checking allSinks vs sinkMap accomplish?  I thought they were
kept synchronized, except for pseudo sinks.

[apacible, 2016/05/26 17:20:46]

Ah, I thought the WebUI filtered out sinks by cast modes rather than the MR
side.

             this.sinkMap_[this.currentRoute_.sinkId].name : '';
       case media_router.MediaRouterView.SINK_LIST:
       case media_router.MediaRouterView.FILTER:
@@ -1571,6 +1600,28 @@ 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) {
+    /** @type {{route: !media_router.Route}} */
+    var detail = event.detail;
+    this.currentLaunchingSinkId_ = detail.route.sinkId;
+    this.launchingSinkAwaitingRouteClose_ = true;
+    this.fire('close-route-for-new-media', detail);

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

Fire 'close-route-click' (or 'close-route' and rename it in the current usage),
since the event handler does the same thing.

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

Done.

+    this.showSinkList_();
+    this.maybeReportUserFirstAction(
+        media_router.MediaRouterUserAction.START_LOCAL);
+  },
+
+  /**
    * 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 +1987,14 @@ 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.launchingSinkAwaitingRouteClose_ &&
+        !(this.currentLaunchingSinkId_ in this.sinkToRouteMap_) &&
+        this.currentLaunchingSinkId_ in this.sinkMap_) {
+      this.showOrCreateRoute_(this.sinkMap_[this.currentLaunchingSinkId_]);
+    }
   },
 
   /**
@@ -2157,7 +2216,9 @@ Polymer({
       this.fire('navigate-sink-list-to-details');
       this.maybeReportUserFirstAction(
           media_router.MediaRouterUserAction.STATUS_REMOTE);
-    } else if (this.currentLaunchingSinkId_ == '') {
+    } else if ((this.launchingSinkAwaitingRouteClose_ &&
+                this.currentLaunchingSinkId_ == sink.id) ||
+               this.currentLaunchingSinkId_ == '') {
       // Allow one launch at a time.
       var selectedCastModeValue =
           this.shownCastModeValue_ == media_router.CastModeType.AUTO ?
@@ -2184,7 +2245,11 @@ Polymer({
             performance.now() - this.populatedSinkListSeenTimeMs_;
         this.fire('report-sink-click-time', {timeMs: timeToSelectSink});
       }
-      this.currentLaunchingSinkId_ = sink.id;
+      if (!this.launchingSinkAwaitingRouteClose_) {
+        this.currentLaunchingSinkId_ = sink.id;
+      } else {
+        this.launchingSinkAwaitingRouteClose_ = false;
+      }
       if (sink.isPseudoSink) {
         this.rebuildSinksToShow_();
       }