Add mutual exclusion to new-folder command execution.

Rapidly clicking on the new folder button in the files app acting as a
save-as dialog can cause multiple flows through that process (from
pressing the button through to completing the rename) to run
concurrently. This can cause some strange effects:
- reporting that the directory already exists, despite the name
  intending to be unique;
- getting stuck a state renaming a newly-created directory that hasn't
  been rendered into the file list, causing the app to be effectively
  unresponsive.

Avoid these problems by disallowing execution of the new-folder command
while another is in progress.

Bug: 632270
Change-Id: I48eb43197403bf85ac78e42a6361c972499b008c
Reviewed-on: https://chromium-review.googlesource.com/c/1345687Reviewed-by: Joel Hockey <joelhockey@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Sam McNally <sammc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609978}

ui/file_manager/file_manager/foreground/js/file_manager_commands.js

@@ -624,7 +624,14 @@ CommandHandler.COMMANDS_['new-folder'] = (function() {
    * @constructor
    * @struct
    */
-  var NewFolderCommand = function() {};
+  var NewFolderCommand = function() {
+    /**
+     * Whether a new-folder is in progress.
+     * @type {boolean}
+     * @private
+     */
+    this.busy_ = false;
+  };
 
   /**
    * @param {!Event} event Command event.
@@ -648,14 +655,15 @@ CommandHandler.COMMANDS_['new-folder'] = (function() {
     var directoryModel = fileManager.directoryModel;
     var directoryTree = fileManager.ui.directoryTree;
     var listContainer = fileManager.ui.listContainer;
+    this.busy_ = true;
 
-    this.generateNewDirectoryName_(targetDirectory).then(function(newName) {
+    this.generateNewDirectoryName_(targetDirectory).then((newName) => {
       if (!executedFromDirectoryTree)
         listContainer.startBatchUpdates();
 
       return new Promise(targetDirectory.getDirectory.bind(targetDirectory,
           newName,
-          {create: true, exclusive: true})).then(function(newDirectory) {
+          {create: true, exclusive: true})).then((newDirectory) => {
             metrics.recordUserAction('CreateNewFolder');
 
             // Select new directory and start rename operation.
@@ -665,19 +673,24 @@ CommandHandler.COMMANDS_['new-folder'] = (function() {
               fileManager.directoryTreeNamingController.attachAndStart(
                   assert(fileManager.ui.directoryTree.selectedItem), false,
                   null);
+              this.busy_ = false;
             } else {
               directoryModel.updateAndSelectNewDirectory(
-                  newDirectory).then(function() {
+                  newDirectory).then(() => {
                 listContainer.endBatchUpdates();
                 fileManager.namingController.initiateRename();
-              }, function() {
+                this.busy_ = false;
+              }, () => {
                 listContainer.endBatchUpdates();
+                this.busy_ = false;
               });
             }
-          }, function(error) {
+          }, (error) => {
             if (!executedFromDirectoryTree)
               listContainer.endBatchUpdates();
 
+            this.busy_ = false;
+
             fileManager.ui.alertDialog.show(
                 strf('ERROR_CREATING_FOLDER',
                      newName,
@@ -737,6 +750,9 @@ CommandHandler.COMMANDS_['new-folder'] = (function() {
           CommandUtil.hasCapability([directoryEntry], 'canAddChildren');
       event.command.setHidden(false);
     }
+    if (this.busy_) {
+      event.canExecute = false;
+    }
   };
 
   return new NewFolderCommand();