Make downloads list keyboard shortcuts more consistent.

chrome/browser/resources/downloads/downloads.js

Index: chrome/browser/resources/downloads/downloads.js
diff --git a/chrome/browser/resources/downloads/downloads.js b/chrome/browser/resources/downloads/downloads.js
index fd7ccc9e6dee71dd48d02317fc2fb38d95c60fa6..381da60542b130eec5592551f5bf8db094703f13 100644
--- a/chrome/browser/resources/downloads/downloads.js
+++ b/chrome/browser/resources/downloads/downloads.js
@@ -77,6 +77,112 @@ function createButton(onclick, value) {
 }
 
 ///////////////////////////////////////////////////////////////////////////////
+// DownloadFocusRow:
+
+/**
+ * Provides an implementation for a single column grid.
+ * @param {Node} boundary Focus events are ignored outside of this node.
+ * @param {Download} node The Download representing this row.
+ * @extends {cr.ui.FocusRow}
+ */
+DownloadFocusRow = function(boundary, node) {
+  cr.ui.FocusRow.call(this, boundary, node.node);
+
+  // Add all clickable elements as a row into the grid.
+  this.addFocusRow_(node.nodeFileLink_, 'name');
+  this.addFocusRow_(node.nodeURL_, 'url');
+  this.addFocusRow_(node.controlShow_, 'show');
+  this.addFocusRow_(node.controlRetry_, 'retry');
+  this.addFocusRow_(node.controlPause_, 'pause');
+  this.addFocusRow_(node.controlResume_, 'resume');
+  this.addFocusRow_(node.controlRemove_, 'remove');
+  this.addFocusRow_(node.controlCancel_, 'cancel');
+
+  // Only one set of these two buttons will be added to a download row at a
+  // time. They have the same type so that focus is handled well in case
+  // there is a dangerous download right next to a malicious download.
+  this.addFocusRow_(node.malwareSave_, 'save');
+  this.addFocusRow_(node.malwareDiscard_, 'discard');
+  this.addFocusRow_(node.dangerSave_, 'save');
+  this.addFocusRow_(node.dangerDiscard_, 'discard');
+
+  this.addFocusRow_(node.controlByExtensionLink_, 'extension');
+};
+
+DownloadFocusRow.prototype = {
+  __proto__: cr.ui.FocusRow.prototype,
+
+  /** @override */
+  getEquivalentElement: function(element) {
+    if (this.contains(element))
+      return element;
+
+    // All elements default to another element with the same type.
+    var query = '[column-type="' + element.getAttribute('column-type') + '"]';
+    var ret = this.getMatch(query);
+
+    // The following element types are at the same UI level.
+    if (!ret) {
+      switch (element.getAttribute('column-type')) {
+        case ('show'):
+        case ('retry'):
+        case ('pause'):
+        case ('resume'):
+        case ('remove'):
+        case ('cancel'):
+          ret = this.getMatch('[column-type="show"]') ||
+                this.getMatch('[column-type="retry"]') ||
+                this.getMatch('[column-type="pause"]') ||
+                this.getMatch('[column-type="resume"]') ||
+                this.getMatch('[column-type="remove"]') ||
+                this.getMatch('[column-type="cancel"]');
+          break;
+      }
+    }
+
+    // Any other miss should return the first rowElement.
+    return ret || this.rowElements[0];
+  },
+
+  /**
+   * Add an element if it exists in this FocusRow and is focusable.
+   * @param {Element} element The element that should be added.
+   * @param {string} type The type to use for the element.
+   * @private
+   */
+  addFocusRow_: function(element, type) {
+    if (this.shouldFocus_(element)) {
+      this.setFocusableElement(element);
+      element.setAttribute('column-type', type);
+    }
+  },
+
+  /**
+   * Determines if element should be focusable.
+   * @param {!Element} element
+   * @return {bool}
+   * @private
+   */
+  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. This is necessary because of the
+    // case where a node has display set to something other than 'none', but it
+    // has an ancestor with display == 'none'.
+    if (element.parentElement)
+      return this.shouldFocus_(element.parentElement);
+
+    return true;
+  },
+};
+
+///////////////////////////////////////////////////////////////////////////////
 // Downloads
 /**
  * Class to hold all the information about the visible downloads.
@@ -91,6 +197,7 @@ function Downloads() {
   this.node_ = $('downloads-display');
   this.summary_ = $('downloads-summary-text');
   this.searchText_ = '';
+  this.focusGrid_ = new cr.ui.FocusGrid();
 
   // Keep track of the dates of the newest and oldest downloads so that we
   // know where to insert them.
@@ -176,6 +283,23 @@ Downloads.prototype.updateResults = function() {
 
   if (loadTimeData.getBoolean('allow_deleting_history'))
     $('clear-all').hidden = !hasDownloads || this.searchText_.length > 0;
+
+  this.rebuildFocusGrid_();
+};
+
+/**
+ * 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) {
+    this.focusGrid_.addRow(new DownloadFocusRow(this.node_,
+                                                this.downloads_[keys[i]]));
+  }
 };
 
 /**