Let the description text in the preview panels managed by PreviewPanel class.

chrome/browser/resources/file_manager/js/file_selection.js

 // Copyright (c) 2012 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';
 
 /**
  * The current selection object.
  *
  * @param {FileManager} fileManager FileManager instance.
@@ skipping 210 matching lines @@
     }
   }
 
   this.updateOkButton();
 
   if (this.selectionUpdateTimer_) {
     clearTimeout(this.selectionUpdateTimer_);
     this.selectionUpdateTimer_ = null;
   }
 
-  this.hideCalculating_();
-
   // The rest of the selection properties are computed via (sometimes lengthy)
   // asynchronous calls. We initiate these calls after a timeout. If the
   // selection is changing quickly we only do this once when it slows down.
 
   var updateDelay = 200;
   var now = Date.now();
   if (now > (this.lastFileSelectionTime_ || 0) + updateDelay) {
     // The previous selection change happened a while ago. Update the UI soon.
     updateDelay = 0;
   }
   this.lastFileSelectionTime_ = now;
 
   this.selectionUpdateTimer_ = setTimeout(function() {
     this.selectionUpdateTimer_ = null;
     if (this.selection == selection)
       this.updateFileSelectionAsync(selection);
   }.bind(this), updateDelay);
 };
 
 /**
- * Clears the primary UI selection elements.
- */
-FileSelectionHandler.prototype.clearUI = function() {
-  this.previewThumbnails_.textContent = '';
-  this.previewText_.textContent = '';
-  this.hideCalculating_();
-  this.taskItems_.hidden = true;
-  this.okButton_.disabled = true;
-};
-
-/**
  * Updates the Ok button enabled state.
  *
  * @return {boolean} Whether button is enabled.
  */
 FileSelectionHandler.prototype.updateOkButton = function() {
   var selectable;
   var dialogType = this.fileManager_.dialogType;
 
   if (dialogType == DialogType.SELECT_FOLDER ||
       dialogType == DialogType.SELECT_UPLOAD_FOLDER) {
@@ skipping 34 matching lines @@
   * @return {boolean} True if all files in the current selection are
   *                   available.
   */
 FileSelectionHandler.prototype.isFileSelectionAvailable = function() {
   return !this.fileManager_.isOnDrive() ||
       !this.fileManager_.isDriveOffline() ||
       this.selection.allDriveFilesPresent;
 };
 
 /**
- * Update the selection summary in preview panel.
- *
- * @private
- */
-FileSelectionHandler.prototype.updatePreviewPanelText_ = function() {
-  var selection = this.selection;
-  if (selection.totalCount <= 1) {
-    // Hides the preview text if zero or one file is selected. We shows a
-    // breadcrumb list instead on the preview panel.
-    this.hideCalculating_();
-    this.previewText_.textContent = '';
-    return;
-  }
-
-  var text = '';
-  if (selection.totalCount == 1) {
-    text = selection.entries[0].name;
-  } else if (selection.directoryCount == 0) {
-    text = strf('MANY_FILES_SELECTED', selection.fileCount);
-  } else if (selection.fileCount == 0) {
-    text = strf('MANY_DIRECTORIES_SELECTED', selection.directoryCount);
-  } else {
-    text = strf('MANY_ENTRIES_SELECTED', selection.totalCount);
-  }
-
-  if (selection.bytesKnown) {
-    this.hideCalculating_();
-    if (selection.showBytes) {
-      var bytes = util.bytesToString(selection.bytes);
-      text += ', ' + bytes;
-    }
-  } else {
-    this.showCalculating_();
-  }
-
-  this.previewText_.textContent = text;
-};
-
-/**
- * Displays the 'calculating size' label.
- *
- * @private
- */
-FileSelectionHandler.prototype.showCalculating_ = function() {
-  if (this.animationTimeout_) {
-    clearTimeout(this.animationTimeout_);
-    this.animationTimeout_ = null;
-  }
-
-  var dotCount = 0;
-
-  var advance = function() {
-    this.animationTimeout_ = setTimeout(advance, 1000);
-
-    var s = this.calculatingSize_.textContent;
-    s = s.replace(/(\.)+$/, '');
-    for (var i = 0; i < dotCount; i++) {
-      s += '.';
-    }
-    this.calculatingSize_.textContent = s;
-
-    dotCount = (dotCount + 1) % 3;
-  }.bind(this);
-
-  var start = function() {
-    this.calculatingSize_.hidden = false;
-    advance();
-  }.bind(this);
-
-  this.animationTimeout_ = setTimeout(start, 500);
-};
-
-/**
- * Hides the 'calculating size' label.
- *
- * @private
- */
-FileSelectionHandler.prototype.hideCalculating_ = function() {
-  if (this.animationTimeout_) {
-    clearTimeout(this.animationTimeout_);
-    this.animationTimeout_ = null;
-  }
-  this.calculatingSize_.hidden = true;
-};
-
-/**
  * Calculates async selection stats and updates secondary UI elements.
  *
  * @param {FileSelection} selection The selection object.
  */
 FileSelectionHandler.prototype.updateFileSelectionAsync = function(selection) {
   if (this.selection != selection) return;
 
   // Update the file tasks.
   if (this.fileManager_.dialogType == DialogType.FULL_PAGE &&
       selection.directoryCount == 0 && selection.fileCount > 0) {
     selection.createTasks(function() {
       if (this.selection != selection)
         return;
       selection.tasks.display(this.taskItems_);
       selection.tasks.updateMenuItem();
     }.bind(this));
   } else {
     this.taskItems_.hidden = true;
   }
 
   // Update preview panels.
   var wasVisible = this.previewPanel_.visible;
   var thumbnailEntries;
   if (selection.totalCount == 0) {
     thumbnailEntries = [
       this.fileManager_.getCurrentDirectoryEntry()
     ];
   } else {
     thumbnailEntries = selection.entries;
-    if (selection.totalCount != 1) {
-      selection.computeBytes(function() {
-        if (this.selection != selection)
-          return;
-        this.updatePreviewPanelText_();
-      }.bind(this));
-    }
   }
-  this.previewPanel_.entries = selection.entries;
-  this.updatePreviewPanelText_();
+  this.previewPanel_.setSelection(selection);
   this.showPreviewThumbnails_(thumbnailEntries);
 
   // Update breadcrums.
   var updateTarget = null;
   var path = this.fileManager_.getCurrentDirectory();
   if (selection.totalCount == 1) {
     // Shows the breadcrumb list when a file is selected.
     updateTarget = selection.entries[0].fullPath;
   } else if (selection.totalCount == 0 &&
              this.previewPanel_.visible) {
@@ skipping 228 matching lines @@
   style.left = (boxWidth - imageWidth) / 2 + 'px';
   style.top = (boxHeight - imageHeight) / 2 + 'px';
   style.position = 'relative';
 
   util.applyTransform(largeImage, transform);
 
   largeImageBox.appendChild(largeImage);
   largeImageBox.style.zIndex = 1000;
   return true;
 };