Update chrome.metricsPrivate externs and make closure fixes

ui/file_manager/image_loader/image_loader_client_unittest.js

 // 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.
 
 'use strict';
 
 var chrome = {
   metricsPrivate: {
+    MetricTypeType: {
+      HISTOGRAM_LOG: 'histogram-log',
+      HISTOGRAM_LINEAR: 'histogram-linear'
+    },
     recordPercentage: function() {},
     recordValue: function() {}
   },
   i18n: {
     getMessage: function() {}
   }
 };
 
 /**
  * Lets the client to load URL and returns the local cache (not caches in the
@@ skipping 58 matching lines @@
       loadAndCheckCacheUsed(client, 'data:URI', {cache: true}).
       then(function(cacheUsed) {
         assertFalse(cacheUsed);
         return loadAndCheckCacheUsed(client, 'data:URI', {cache: true});
       }).
       then(function(cacheUsed) {
         assertFalse(cacheUsed);
       }),
       callback);
 }