Added Home, end, PageUp, PageDown support in the ChromeVox menu

BUG=646238
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2350103003
Cr-Commit-Position: refs/heads/master@{#419567}

chrome/browser/resources/chromeos/chromevox/cvox2/background/panel.js

@@ -442,6 +442,20 @@ Panel.activateMenu = function(menu) {
   }
 };
 
+/**
+ * Sets the index of the current active menu to be 0.
+ */
+Panel.scrollToTop = function() {
+  this.activeMenu_.scrollToTop();
+};
+
+/**
+ * Sets the index of the current active menu to be the last index.
+ */
+Panel.scrollToBottom = function() {
+  this.activeMenu_.scrollToBottom();
+};
+
 /**
  * Advance the index of the current active menu by |delta|.
  * @param {number} delta The number to add to the active menu index.
@@ -530,6 +544,18 @@ Panel.onKeyDown = function(event) {
     case 'Escape':
       Panel.closeMenusAndRestoreFocus();
       break;
+    case 'PageUp':
+      Panel.advanceItemBy(10);
+      break;
+    case 'PageDown':
+      Panel.advanceItemBy(-10);
+      break;
+    case 'Home':
+      Panel.scrollToTop();
+      break;
+    case 'End':
+      Panel.scrollToBottom();
+      break;
     case 'Enter':
     case ' ':  // Space
       Panel.pendingCallback_ = Panel.getCallbackForCurrentItem();

chrome/browser/resources/chromeos/chromevox/cvox2/background/panel_menu.js

@@ -168,6 +168,22 @@ PanelMenu.prototype = {
     this.items_[this.activeIndex_].element.focus();
   },
 
+  /**
+   * Sets the active menu item index to be 0.
+   */
+  scrollToTop: function() {
+    this.activeIndex_ = 0;
+    this.items_[this.activeIndex_].element.focus();
+  },
+
+  /**
+   * Sets the active menu item index to be the last index.
+   */
+  scrollToBottom: function() {
+    this.activeIndex_ = this.items_.length - 1;
+    this.items_[this.activeIndex_].element.focus();
+  },
+
   /**
    * Get the callback for the active menu item.
    * @return {Function} The callback.