Update chrome.metricsPrivate externs and make closure fixes

chrome/browser/resources/google_now/background.js

 // Copyright (c) 2013 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.
 
 'use strict';
 
 /**
  * @fileoverview The event page for Google Now for Chrome implementation.
  * The Google Now event page gets Google Now cards from the server and shows
  * them as Chrome notifications.
@@ skipping 259 matching lines @@
                     // added before it.
 };
 
 /**
  * Records a Google Now Event.
  * @param {GoogleNowEvent} event Event identifier.
  */
 function recordEvent(event) {
   var metricDescription = {
     metricName: 'GoogleNow.Event',
-    type: 'histogram-linear',
+    type: chrome.metricsPrivate.MetricTypeType.HISTOGRAM_LINEAR,
     min: 1,
     max: GoogleNowEvent.EVENTS_TOTAL,
     buckets: GoogleNowEvent.EVENTS_TOTAL + 1
   };
 
   chrome.metricsPrivate.recordValue(metricDescription, event);
 }
 
 /**
  * Records a notification clicked event.
@@ skipping 1204 matching lines @@
             lastPollNowPayloads: items.lastPollNowPayloads,
             notificationGroups: items.notificationGroups
           });
 
           pollOptedInWithRecheck();
         }
       });
     });
   }
 });