Quick View UMA: export how quick view was opened.

ui/file_manager/file_manager/foreground/js/quick_view_uma.js

 // Copyright 2016 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.
 
 /**
  * UMA exporter for Quick View.
  *
  * @param {!VolumeManagerWrapper} volumeManager
  *
  * @constructor
  */
 function QuickViewUma(volumeManager) {
 
   /**
    * @type {!VolumeManagerWrapper}
    * @private
    */
   this.volumeManager_ = volumeManager;
 }
 
 /**
+ * In which way quick view was opened.
+ * @enum {!string}

[fukino, 2017/01/12 03:46:01]

nit: ! is redundant

[oka, 2017/01/12 04:14:02]

Oops. Done.

+ * @const
+ */
+QuickViewUma.WayToOpen = {
+  CONTEXT_MENU: 'contextMenu',
+  SPACE_KEY: 'spaceKey',
+};
+
+/**
+ * The order should be consistnet with the definition  in histograms.xml.
+ *
+ * @const {!Array<QuickViewUma.WayToOpen>}
+ * @private
+ */
+QuickViewUma.WayToOpenValues_ = [
+  QuickViewUma.WayToOpen.CONTEXT_MENU,
+  QuickViewUma.WayToOpen.SPACE_KEY,
+];
+
+/**
  * Keep the order of this in sync with FileManagerVolumeType in
  * tools/metrics/histograms/histograms.xml.
  *
  * @type {!Array<VolumeManagerCommon.VolumeType>}
  * @const
  */
 QuickViewUma.VolumeType = [
   VolumeManagerCommon.VolumeType.DRIVE,
   VolumeManagerCommon.VolumeType.DOWNLOADS,
   VolumeManagerCommon.VolumeType.REMOVABLE,
@@ skipping 24 matching lines @@
  * @param {!FileEntry} entry
  */
 QuickViewUma.prototype.onEntryChanged = function(entry) {
   this.exportFileType_(entry, 'QuickView.FileType');
 };
 
 /**
  * Exports UMA based on the entry selected when Quick View is opened.
  *
  * @param {!FileEntry} entry
+ * @param {!QuickViewUma.WayToOpen} wayToOpen

[fukino, 2017/01/12 03:46:01]

nit: We usually don't use ! for enum types.

  */
-QuickViewUma.prototype.onOpened = function(entry) {
+QuickViewUma.prototype.onOpened = function(entry, wayToOpen) {
   this.exportFileType_(entry, 'QuickView.FileTypeOnLaunch');
+  metrics.recordEnum(
+      'QuickView.WayToOpen', wayToOpen, QuickViewUma.WayToOpenValues_);
+
   var volumeType = this.volumeManager_.getVolumeInfo(entry).volumeType;
   if (QuickViewUma.VolumeType.includes(volumeType)) {
     metrics.recordEnum(
         'QuickView.VolumeType', volumeType, QuickViewUma.VolumeType);
   } else {
     console.error('Unknown volume type: ' + volumeType);
   }
 };