Some perf improvements to sheriff-o-matics updates.

Tools/GardeningServer/model/ct-sheriff-failure-group-data.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.
 -->
 
 <link rel="import" href="ct-commit-list.html">
 
 <script>
 function CTSheriffFailureGroupData(failures, commitList) {
@@ skipping 10 matching lines @@
 
 CTSheriffFailureGroupData.prototype.dataToExamine = function() {
   return this.failures;
 };
 
 CTSheriffFailureGroupData.prototype.failureKeys = function() {
   return this.failures.map(function(failure) {
     return failure.keys();
   }).flatten();
 };
+
+CTSheriffFailureGroupData.prototype.failedOnce = function() {

[esprehn, 2014/09/10 03:59:13]

This is much better.

+  var totalFailures = 0;
+  for (var i = 0; i < this.failures.length; i++) {
+    var resultNodes = this.failures[i].resultNodesByBuilder;
+    for (var r in resultNodes) {
+      totalFailures += resultNodes[r].failingBuildCount;
+      if (totalFailures > 1)
+        return false;
+    }
+  }
+  return totalFailures == 1;
+}
 </script>