Show a local folder's size in QuickView.

ui/file_manager/file_manager/foreground/js/metadata_box_controller.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.
 
 /**
  * Controller of metadata box.
  *
  * @param{!MetadataModel} metadataModel
  * @param{!FilesMetadataBox} metadataBox
  * @param{!FilesQuickView} quickView
@@ skipping 72 matching lines @@
       .get(
           [entry], MetadataBoxController.GENERAL_METADATA_NAME.concat(
                        ['hosted', 'externalFileUrl']))
       .then(this.onGeneralMetadataLoaded_.bind(this, entry));
 };
 
 /**
  * Update metadata box with general file information.
  * Then retrieve file specific metadata if any.
  *
- * @param {!FileEntry} entry
+ * @param {!Entry} entry
  * @param {!Array<!MetadataItem>} items
  *
  * @private
  */
 MetadataBoxController.prototype.onGeneralMetadataLoaded_ = function(
     entry, items) {
   var type = FileType.getType(entry).type;
   var item = items[0];
 
   this.metadataBox_.type = type;
   if (item.size) {
     this.metadataBox_.size =
         this.fileMetadataFormatter_.formatSize(item.size, item.hosted);
   }
+  if (entry.isDirectory) {
+    this.setDirectorySize_( /** @type {!DirectoryEntry} */ (entry));
+  }
   if (item.modificationTime) {
     this.metadataBox_.modificationTime =
         this.fileMetadataFormatter_.formatModDate(item.modificationTime);
   }
 
   if (item.externalFileUrl) {
     this.metadataModel_.get([entry], ['contentMimeType']).then(function(items) {
       var item = items[0];
       this.metadataBox_.mediaMimeType = item.contentMimeType;
     }.bind(this));
@@ skipping 22 matching lines @@
           .then(function(items) {
             var item = items[0];
             this.metadataBox_.imageHeight = item.imageHeight;
             this.metadataBox_.imageWidth = item.imageWidth;
             this.metadataBox_.mediaArtist = item.mediaArtist;
             this.metadataBox_.mediaTitle = item.mediaTitle;
           }.bind(this));
     }
   }
 };
+
+/**
+ * Set a current directory's size in metadata box.
+ *
+ * @param {!DirectoryEntry} entry
+ *
+ * @private
+ */
+MetadataBoxController.prototype.setDirectorySize_ = function(entry) {
+  if (!entry.isDirectory)
+    return;
+
+  this.metadataBox_.isSizeLoading = true;
+  chrome.fileManagerPrivate.getDirectorySize(entry,
+      function(size) {
+        if(this.quickViewModel_.getSelectedEntry() != entry) {
+          return;
+        }
+        if(chrome.runtime.lastError) {
+          this.metadataBox_.isSizeLoading = false;
+          return;
+        }
+
+        this.metadataBox_.isSizeLoading = false;
+        this.metadataBox_.size =
+        this.fileMetadataFormatter_.formatSize(size, true);
+      }.bind(this));
+};