Shows a launch spinner next to a sink once it is selected to create a route. The launch spinner sur…

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

Index: chrome/browser/resources/media_router/elements/media_router_container/media_router_container.html
diff --git a/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.html b/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.html
index 2f7b84a3224005eaf666ddbd33b74df7f7714790..3b4efb364970dbe269d70c9752f8c512bf8dac0b 100644
--- a/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.html
+++ b/chrome/browser/resources/media_router/elements/media_router_container/media_router_container.html
@@ -68,9 +68,13 @@
             <div class="sink-content">
               <div>
                 <!-- TODO(apacible): Show device icon based on device type. -->
-                <iron-icon icon="hardware:tv"
+                <iron-icon icon="hardware:tv" hidden$="[[item.isLaunching]]"
                     class$="[[computeSinkIconClass_(item.id, sinkToRouteMap_)]]">
                 </iron-icon>
+                <template is="dom-if" if="[[item.isLaunching]]">

[apacible, 2015/08/10 14:13:26]

Switch to just using modifying the hidden attribute rather than using a
conditional template (template is more costly).

From the primer:
"Note, since it is generally much faster to hide/show elements rather than
create/destroy them, conditional templates are only useful to save initial
creation cost when the elements being stamped are relatively heavyweight and the
conditional may rarely (or never) be true in given useages. Otherwise, liberal
use of conditional templates can actually add significant runtime performance
overhead.

...

Hiding/showing elements is as simple as attribute-binding to the hidden
attribute (e.g. <div hidden$="{{!shouldShow}}">), and does not require
conditional templating at all."

More info:
https://github.com/Polymer/polymer/blob/master/PRIMER.md#conditional-template

[haibinlu, 2015/08/11 01:31:46]

per offline discussion, launch is much less often than opening UI to show the
list, and only one launch allowed.

[apacible, 2015/08/11 18:29:58]

Acknowledged.

+                  <paper-spinner class="sink-icon" active>
+                  </paper-spinner>
+                </template>
               </div>
               <div>
                 <div class="sink-text">