Reland r221579: Files.app: Let the PreviewPanel class control the visibility of the preview panel.

chrome/browser/resources/file_manager/js/ui/preview_panel.js

 // Copyright (c) 2013 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';
 
 /**
  * PreviewPanel UI class.
  * @param {HTMLElement} element DOM Element of preview panel.
  * @param {PreviewPanel.VisibilityType} visibilityType Initial value of the
@@ skipping 74 matching lines @@
 PreviewPanel.Event = Object.freeze({
   // Event to be triggered at the end of visibility change.
   VISIBILITY_CHANGE: 'visibilityChange'
 });
 
 /**
  * Visibility type of the preview panel.
  */
 PreviewPanel.VisibilityType = Object.freeze({
   // Preview panel always shows.
-  ALWAYS: 'always',
+  ALWAYS_VISIBLE: 'alwaysVisible',
   // Preview panel shows when the entries property are set.
   AUTO: 'auto',
   // Preview panel does not show.
-  HIDDEN: 'hidden'
+  ALWAYS_HIDDEN: 'alwaysHidden'
 });
 
 /**
  * @private
  */
 PreviewPanel.Visibility_ = Object.freeze({
   VISIBLE: 'visible',
   HIDING: 'hiding',
   HIDDEN: 'hidden'
 });
@@ skipping 27 matching lines @@
   set visibilityType(visibilityType) {
     this.visibilityType_ = visibilityType;
     this.updateVisibility_();
   },
 
   get visible() {
     return this.element_.getAttribute('visibility') ==
         PreviewPanel.Visibility_.VISIBLE;
   },
 
+  /**
+   * Obtains the height of preview panel.
+   * @return {number} Height of preview panel.
+   */
   get height() {
     this.height_ = this.height_ || this.element_.clientHeight;
     return this.height_;
   }
 };
 
 /**
  * Initializes the element.
  */
 PreviewPanel.prototype.initialize = function() {
   this.element_.addEventListener('webkitTransitionEnd',
                                  this.onTransitionEnd_.bind(this));
   this.updateVisibility_();
 };
 
 /**
  * Update the visibility of the preview panel.
  * @private
  */
 PreviewPanel.prototype.updateVisibility_ = function() {
   // Get the new visibility value.
   var visibility = this.element_.getAttribute('visibility');
   var newVisible = null;
   switch (this.visibilityType_) {
-    case PreviewPanel.VisibilityType.ALWAYS:
+    case PreviewPanel.VisibilityType.ALWAYS_VISIBLE:
       newVisible = true;
       break;
     case PreviewPanel.VisibilityType.AUTO:
       newVisible = this.entries_.length != 0 ||
                    !PathUtil.isRootPath(this.currentPath_);
       break;
-    case PreviewPanel.VisibilityType.HIDDEN:
+    case PreviewPanel.VisibilityType.ALWAYS_HIDDEN:
       newVisible = false;
       break;
     default:
       console.error('Invalid visibilityType.');
       return;
   }
 
   // If the visibility has been already the new value, just return.
   if ((visibility == PreviewPanel.Visibility_.VISIBLE && newVisible) ||
       (visibility == PreviewPanel.Visibility_.HIDDEN && !newVisible))
@@ skipping 15 matching lines @@
  */
 PreviewPanel.prototype.onTransitionEnd_ = function(event) {
   if (event.target != this.element_ || event.propertyName != 'opacity')
     return;
   var visibility = this.element_.getAttribute('visibility');
   if (visibility != PreviewPanel.Visibility_.HIDING)
     return;
   this.element_.setAttribute('visibility', PreviewPanel.Visibility_.HIDDEN);
   cr.dispatchSimpleEvent(this, PreviewPanel.Event.VISIBILITY_CHANGE);
 };