Make downloads list keyboard shortcuts more consistent.

chrome/browser/resources/downloads/downloads.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.
 
 // TODO(jhawkins): Use hidden instead of showInline* and display:none.
 
 /**
  * The type of the download object. The definition is based on
  * chrome/browser/ui/webui/downloads_dom_handler.cc:CreateDownloadItemValue()
  * @typedef {{by_ext_id: (string|undefined),
@@ skipping 59 matching lines @@
  */
 function createButton(onclick, value) {
   var button = document.createElement('input');
   button.type = 'button';
   button.value = value;
   button.onclick = onclick;
   return button;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
+// DownloadFocusObserver:
+
+/**
+ * @constructor
+ * @implements {cr.ui.FocusRow.Observer}
+ */
+function DownloadFocusObserver() {}
+
+DownloadFocusObserver.prototype = {
+  /** @override */
+  onActivate: function(row) {},
+
+  /** @override */
+  onDeactivate: function(row) {},
+
+  /**
+   * @param {Element} item The row item to find a a row element for.
+   * @return {Element} |row|'s "active" element.
+   * @override
+   */
+  getRowElement: function(item) {
+    return findAncestorByClass(item, 'download');
+  },
+
+  /** @override */
+  onElementIdMiss: function(row, expectedId) {
+    // These are at the same level visually, so focus the first available one if
+    // it exists.
+    var remaining = ['show', 'retry', 'pause', 'resume', 'remove', 'cancel'];
+    if (remaining.indexOf(expectedId) > -1) {
+      for (var i = 0; i < remaining.length; ++i) {
+        if (row.elementIds.indexOf(remaining[i]) > -1)
+          return remaining[i];
+      }
+    }
+
+    // Select the first item that is focusable if nothing else worked.
+    return row.elementIds[0];
+  },
+};
+
+///////////////////////////////////////////////////////////////////////////////
 // Downloads
 /**
  * Class to hold all the information about the visible downloads.
  * @constructor
  */
 function Downloads() {
   /**
    * @type {!Object.<string, Download>}
    * @private
    */
   this.downloads_ = {};
   this.node_ = $('downloads-display');
   this.summary_ = $('downloads-summary-text');
   this.searchText_ = '';
+  this.focusGrid_ = new cr.ui.FocusGrid(this.node_,
+                                        new DownloadFocusObserver());
 
   // Keep track of the dates of the newest and oldest downloads so that we
   // know where to insert them.
   this.newestTime_ = -1;
 
   // Icon load request queue.
   this.iconLoadQueue_ = [];
   this.isIconLoading_ = false;
 
   this.progressForeground1_ = new Image();
@@ skipping 65 matching lines @@
   var noDownloadsOrResults = $('no-downloads-or-results');
   noDownloadsOrResults.textContent = loadTimeData.getString(
       this.searchText_ ? 'no_search_results' : 'no_downloads');
 
   var hasDownloads = this.size() > 0;
   this.node_.hidden = !hasDownloads;
   noDownloadsOrResults.hidden = hasDownloads;
 
   if (loadTimeData.getBoolean('allow_deleting_history'))
     $('clear-all').hidden = !hasDownloads || this.searchText_.length > 0;
+
+  this.rebuildFocusGrid_();
 };
 
 /**
+ * Determines if element should be focusable.
+ * @param {!Element} element
+ * @return {bool}
+ * @private
+ */
+Downloads.shouldFocus_ = function(element) {
+  if (!element)
+    return false;
+
+  // Hidden elements are not focusable.
+  var style = window.getComputedStyle(element);
+  if (style.visibility == 'hidden' || style.display == 'none')
+    return false;
+
+  // Verify that all ancestors are focusable.
+  if (element.parentElement)
+    return Downloads.shouldFocus_(element.parentElement);
+
+  return true;
+};
+
+/**
+ * Will add an element to |focusRow| if it can be focused.
+ * @param {cr.ui.FocusRow} focusRow The row to add the element to.
+ * @param {Element} element The element to add.
+ * @param {string} elementId The elementId used for selecting in a grid.
+ * @private
+ */
+Downloads.prototype.addRowElement_ = function(focusRow, element, elementId) {
+  if (Downloads.shouldFocus_(element))
+    focusRow.setFocusableElementId(element, elementId);
+};
+
+/**
+ * Rebuild the focusGrid_ using the elements that each download will have.
+ * @private
+ */
+Downloads.prototype.rebuildFocusGrid_ = function() {
+  this.focusGrid_.destroy();
+
+  // Keys for downloads are in the reverse order of what is displayed.
+  var keys = Object.keys(this.downloads_);
+  for (var i = keys.length - 1; i >= 0; --i) {
+    var node = this.downloads_[keys[i]];
+    var focusRow = this.focusGrid_.createRow();
+
+    // Add all clickable elements as a row into the grid.
+    this.addRowElement_(focusRow, node.nodeFileLink_, 'name');
+    this.addRowElement_(focusRow, node.nodeURL_, 'url');
+    this.addRowElement_(focusRow, node.controlShow_, 'show');
+    this.addRowElement_(focusRow, node.controlRetry_, 'retry');
+    this.addRowElement_(focusRow, node.controlPause_, 'pause');
+    this.addRowElement_(focusRow, node.controlResume_, 'resume');
+    this.addRowElement_(focusRow, node.controlRemove_, 'remove');
+    this.addRowElement_(focusRow, node.controlCancel_, 'cancel');
+
+    // These buttons are mutually exclusive, but they are visually the same.
+    this.addRowElement_(focusRow, node.malwareSave_, 'save');
+    this.addRowElement_(focusRow, node.dangerSave_, 'save');
+    this.addRowElement_(focusRow, node.malwareDiscard_, 'discard');
+    this.addRowElement_(focusRow, node.dangerDiscard_, 'discard');
+
+    this.addRowElement_(focusRow, node.controlByExtensionLink_, 'extension');
+
+    this.focusGrid_.addRow(focusRow);
+  }
+};
+
+/**
  * Returns the number of downloads in the model. Used by tests.
  * @return {number} Returns the number of downloads shown on the page.
  */
 Downloads.prototype.size = function() {
   return Object.keys(this.downloads_).length;
 };
 
 /**
  * Called whenever the downloads lists items have changed (either by being
  * updated, added, or removed).
@@ skipping 786 matching lines @@
     if (Date.now() - start > 50) {
       clearTimeout(resultsTimeout);
       resultsTimeout = setTimeout(tryDownloadUpdatedPeriodically, 5);
       break;
     }
   }
 }
 
 // Add handlers to HTML elements.
 window.addEventListener('DOMContentLoaded', load);