Make onFileTransferUpdated single value from list.

ui/file_manager/file_manager/background/js/drive_sync_handler.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';
 
 /**
  * Handler of the background page for the drive sync events.
  * @param {ProgressCenter} progressCenter Progress center to submit the
  *     progressing items.
@@ skipping 66 matching lines @@
   get syncing() {
     return this.syncing_;
   }
 };
 
 /**
  * Handles file transfer updated events.
  * @param {Array.<FileTransferStatus>} statusList List of drive status.
  * @private
  */
-DriveSyncHandler.prototype.onFileTransfersUpdated_ = function(statusList) {
-  var completed = false;
-  for (var i = 0; i < statusList.length; i++) {
-    var status = statusList[i];
-    switch (status.transferState) {
-      case 'added':
-      case 'in_progress':
-      case 'started':
-        this.updateItem_(status);
-        break;
-      case 'completed':
-      case 'failed':
-        if (status.num_total_jobs === 1)
-          this.removeItem_(status);
-        break;
-      default:
-        throw new Error(
-            'Invalid transfer state: ' + status.transferState + '.');
-    }
+DriveSyncHandler.prototype.onFileTransfersUpdated_ = function(status) {
+  switch (status.transferState) {
+    case 'added':
+    case 'in_progress':
+    case 'started':
+      this.updateItem_(status);
+      break;
+    case 'completed':
+    case 'failed':
+      if (status.num_total_jobs === 1)
+        this.removeItem_(status);
+      break;
+    default:
+      throw new Error(
+          'Invalid transfer state: ' + status.transferState + '.');
   }
 };
 
 /**
  * Updates the item involved with the given status.
  * @param {FileTransferStatus} status Transfer status.
  * @private
  */
 DriveSyncHandler.prototype.updateItem_ = function(status) {
   this.queue_.run(function(callback) {
@@ skipping 66 matching lines @@
       case 'service_unavailable':
         item.message = str('SYNC_SERVICE_UNAVAILABLE_ERROR');
         break;
       case 'misc':
         item.message = strf('SYNC_MISC_ERROR', entry.name);
         break;
     }
     this.progressCenter_.updateItem(item);
   }.bind(this));
 };