Update chrome.metricsPrivate externs and make closure fixes

ui/file_manager/file_manager/common/js/metrics_base.js

 // Copyright (c) 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.
 
 /**
  * @fileoverview Utility methods for accessing chrome.metricsPrivate API.
  *
  * To be included as a first script in main.html
  */
 
@@ skipping 143 matching lines @@
   // Collect invalid values in the overflow bucket at the end.
   if (index < 0 || index >= boundaryValue)
     index = boundaryValue - 1;
 
   // Setting min to 1 looks strange but this is exactly the recommended way
   // of using histograms for enum-like types. Bucket #0 works as a regular
   // bucket AND the underflow bucket.
   // (Source: UMA_HISTOGRAM_ENUMERATION definition in base/metrics/histogram.h)
   var metricDescr = {
     'metricName': metrics.convertName_(name),
-    'type': 'histogram-linear',
+    'type': chrome.metricsPrivate.MetricTypeType.HISTOGRAM_LINEAR,
     'min': 1,
     'max': boundaryValue,
     'buckets': boundaryValue
   };
   metrics.call_('recordValue', [metricDescr, index]);
 };