Add failed_once category to Sheriff-O-Matic.

Tools/GardeningServer/model/ct-failure-group.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 CTFailureGroup(key, data) {
@@ skipping 26 matching lines @@
     bug: bug,
   });
 };
 
 CTFailureGroup.prototype.clearBug = function(bug) {
   return this._annotate({
     bug: undefined,
   });
 };
 
+CTFailureGroup.prototype._failedOnce = function() {
+  var totalFailures = 0;
+  for (var i = 0; i < this.data.dataToExamine().length; i++) {
+    var resultNodes = this.data.dataToExamine()[i].resultNodesByBuilder;
+    Object.keys(resultNodes, function(r) {
+      totalFailures += resultNodes[r].failingBuildCount;
+      if (totalFailures > 1)
+        return false;
+    }.bind(this));
+  }
+  return totalFailures == 1;
+}
+
 CTFailureGroup.prototype._computeProperties = function() {
   this.isSnoozed = Date.now() < this._annotation.snoozeTime;
   if (this.isSnoozed) {
     this.category = 'snoozed';
   } else {
+    if (this._failedOnce()) {
+      this.category = 'failedOnce';
+    } else {
+      this.category = 'default';
+    }
     // FIXME: crbug.com/400397 Split into: Whole step failure, Tree closer, Test failure, Flaky tests
-    this.category = 'default';
   }
 
   this.bug = this._annotation.bug;
   // FIXME: Bug labels would be simpler to implement as a filter in the UI.
   if (this.bug != null)
     this.bugLabel = 'Bug ' + /([0-9]{3,})/.exec(this.bug)[0];
   else
     this.bugLabel = undefined;
 };
 
@@ skipping 45 matching lines @@
   }.bind(this));
 };
 
 CTFailureGroup.fetchAnnotations = function() {
   // FIXME: Fetch annotations from frontend.
   var stored = localStorage.CTFailureGroupAnnotations;
   var annotations = stored ? JSON.parse(stored) : {};
   return Promise.resolve(annotations);
 };
 </script>