Expose the chromium waterfall in sheriff-o-matic.

Tools/GardeningServer/ui/ct-sheriff-o-matic.html

 <!--
 Copyright 2014 The Chromium Authors. All rights reserved.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 -->
 
 <script src="../bower_components/sugar/release/sugar-full.development.js"></script>
 <script src="../scripts/net.js"></script>
 <script src="../scripts/results.js"></script>
 <script src="../scripts/treestatus.js"></script>
@@ skipping 12 matching lines @@
         flex-direction: column;
         height: 100%;
       }
       header {
         -webkit-user-select: none;
         align-items: center;
         background-color: #212121;
         color: white;
         cursor: default;
         display: flex;
+        justify-content: space-between;
         font-size: 1.1em;
       }
       header a, header span {
         color: white;
         display: inline-block;
         padding: 0.25em 4px;
         text-decoration: none;
       }
       core-animated-pages {
         flex: 1;
       }
     </style>
 
     <header>
-      <template if="{{ selected == 0 }}">
-        <span><img src="../favicon.ico"> Auto-sheriff-o-maticon</span>
-      </template>
-      <template if="{{ selected == 1 }}">
-        <a on-click="{{ onBack }}">
-          &lt;&lt; Go back
-        </a>
-      </template>
+      <div>
+        <template if="{{ selected == 0 }}">
+          <span><img src="../favicon.ico"> Auto-sheriff-o-maticon</span>
+        </template>
+        <template if="{{ selected == 1 }}">
+          <a on-click="{{ onBack }}">
+            &lt;&lt; Go back
+          </a>
+        </template>
+      </div>
+      <!-- FIXME: Use a proper polymer component with data binding. -->
+      <select id="tree" on-change="{{ _updateTree }}">
+        <option value="blink">Blink</option>
+        <option value="chromium">Chromium</option>
+      </select>
     </header>
 
     <core-animated-pages selected="{{ selected }}" transitions="slide-from-right">
-      <ct-unexpected-failures on-ct-examine-failures="{{ onExamine }}"></ct-unexpected-failures>
-      <ct-results-panel failures="{{ currentFailures }}"></ct-results-panel>
+      <ct-unexpected-failures tree="{{ tree }}" on-ct-examine-failures="{{ onExamine }}"></ct-unexpected-failures>
+      <ct-results-panel failures="{{ currentFailures }}" tree="{{ tree }}"></ct-results-panel>
     </core-animated-pages>
   </template>
   <script>
     Polymer({
+      // FIXME: Make chromium the default.
+      // That requires updating the select to the right value.
+      tree: 'blink',
       selected: 0,
       currentFailures: [],
 
+      _updateTree: function() {
+        this.tree = this.$.tree.selectedOptions[0].value;
+      },
+
       onBack: function() {
         this.selected = 0;
       },
 
       onExamine: function(event) {
         this.currentFailures = event.detail;
         this.selected = 1;
       },
     });
   </script>
 </polymer-element>