Show a local folder's size in QuickView.

ui/file_manager/file_manager/foreground/js/metadata_box_controller.js

Index: ui/file_manager/file_manager/foreground/js/metadata_box_controller.js
diff --git a/ui/file_manager/file_manager/foreground/js/metadata_box_controller.js b/ui/file_manager/file_manager/foreground/js/metadata_box_controller.js
index 94d8bc8b21446b735103a799aa671dc65d4788bd..afd063bdf25bc71d88cdfd57dbccc9ab0bb1b894 100644
--- a/ui/file_manager/file_manager/foreground/js/metadata_box_controller.js
+++ b/ui/file_manager/file_manager/foreground/js/metadata_box_controller.js
@@ -40,6 +40,12 @@ function MetadataBoxController(
    */
   this.fileMetadataFormatter_ = fileMetadataFormatter;
 
+  /**
+   * @type {Promise.<number>}

[fukino, 2016/09/06 09:12:45]

We don't need '.'. Use Promise<number>

[harukam, 2016/09/06 11:25:24]

Acknowledged.

+   * @private
+   */
+  this.directorySizePromise_ = null;
+
   // TODO(oka): Add storage to persist the value of
   // quickViewModel_.metadataBoxActive.
   /**
@@ -90,7 +96,7 @@ MetadataBoxController.prototype.updateView_ = function() {
  * 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
@@ -105,6 +111,18 @@ MetadataBoxController.prototype.onGeneralMetadataLoaded_ = function(
     this.metadataBox_.size =
         this.fileMetadataFormatter_.formatSize(item.size, item.hosted);
   }
+  if (entry.isDirectory) {
+    this.setDirectorySize_(new Promise(function(resolve, reject) {

[fukino, 2016/09/06 09:12:45]

I think it is better to simply call this.setDirectorySize_(entry) and move the
implementation inside setDirectorySize_.

[harukam, 2016/09/06 11:25:24]

OK. Thanks.

+      chrome.fileManagerPrivate.getDirectorySize(
+          /** @type {!DirectoryEntry} */ (entry),
+          function(size) {
+            if(chrome.runtime.lastError)
+              reject();
+            else
+              resolve(size);
+          });
+    }));
+  }
   if (item.modificationTime) {
     this.metadataBox_.modificationTime =
         this.fileMetadataFormatter_.formatModDate(item.modificationTime);
@@ -147,3 +165,30 @@ MetadataBoxController.prototype.onGeneralMetadataLoaded_ = function(
     }
   }
 };
+
+/**
+ * Set a directory size in metadata box.
+ *
+ * @param {Promise.<number>} directorySizePromise
+ *
+ * @private
+ */
+MetadataBoxController.prototype.setDirectorySize_ = function(
+    directorySizePromise) {
+  this.directorySizePromise_ = directorySizePromise;

[fukino, 2016/09/06 09:12:45]

If you avoid showing the size of the wrong entry, I think keeping track of Entry
instead of the promise will be easier to understand. 

[harukam, 2016/09/06 11:25:24]

Acknowledged.

+  if (!directorySizePromise)
+    return;
+
+  this.metadataBox_.setLoading(true);
+  directorySizePromise.then(function(size) {
+    if(this.directorySizePromise_ != directorySizePromise)
+      return;
+    this.metadataBox_.setLoading(false);
+    this.metadataBox_.size =
+        this.fileMetadataFormatter_.formatSize(size, true);
+  }.bind(this)).catch(function(error) {
+    if(this.directorySizePromise_ != directorySizePromise)
+      return;
+    this.metadataBox_.setLoading(false);
+  }.bind(this));
+};