Fixed flickering "Computing selection" label.

chrome/browser/resources/file_manager/js/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.
 
 /**
  * The current selection object.
  * @param {FileManager} fileManager FileManager instance.
  * @param {Array.<number>} indexes Selected indexes.
  */
 function Selection(fileManager, indexes) {
@@ skipping 173 matching lines @@
         this.filenameInput_.value != this.selection.entries[0].name) {
       this.filenameInput_.value = this.selection.entries[0].name;
     }
   }
 
   this.updateOkButton();
 
   if (this.selectionUpdateTimer_) {
     clearTimeout(this.selectionUpdateTimer_);
     this.selectionUpdateTimer_ = null;
-
-    // The selection is changing quicker than we can update the UI.
-    // Clear the UI.
-    this.clearUI();
   }
 
   if (!indexes.length) {
     this.updatePreviewPanelVisibility_();
     this.updatePreviewPanelText_();
     this.fileManager_.updateContextMenuActionItems(null, false);
     return;
   }
 
-  this.previewText_.textContent = str('COMPUTING_SELECTION');
   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;

[mtomasz, 2013/01/15 01:41:08]

This should work fine, since label is updated after 200 ms with "Calculating
size..." message. Take a look at line #474. Before, we had duplicated "wating"
messages:
1. Computing selection... (IDS_FILE_BROWSER_COMPUTING_SELECTION) shown
immediately.
2. Calculating size... (IDS_FILE_BROWSER_CALCULATING_SIZE) shown after 200 ms.

I removed the first one since it is redundant and caused flickering.

   var now = Date.now();
   if (now > (this.lastSelectionTime_ || 0) + updateDelay) {
     // The previous selection change happened a while ago. Update the UI soon.
     updateDelay = 0;
   }
   this.lastSelectionTime_ = now;
 
   this.selectionUpdateTimer_ = setTimeout(function() {
     this.selectionUpdateTimer_ = null;
     if (this.selection == selection)
@@ skipping 239 matching lines @@
   var commands = this.fileManager_.dialogDom_.querySelectorAll('command');
   for (var i = 0; i < commands.length; i++)
     commands[i].canExecuteChange();
 
   // Update the summary information.
   var onBytes = function() {
     if (this.selection != selection) return;
     this.updatePreviewPanelText_();
   }.bind(this);
   selection.computeBytes(onBytes);
   this.updatePreviewPanelText_();

[mtomasz, 2013/01/15 01:41:08]

Here.

 
   // Inform tests it's OK to click buttons now.
   chrome.test.sendMessage('selection-change-complete');
 
   // Show thumbnails.
   this.showPreviewThumbnails_(selection);
 };
 
 /**
  * Renders preview thumbnails in preview panel.
@@ skipping 179 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;
 };