[Switch Access] Reset keyboard nodes when invalidated

Fixes a bug where pressing shift rendered most of the keyboard
unreachable by rebuilding all of the keyboard nodes.

As a side effect, causes the focus to jump back to the beginning of the
keyboard when shift is engaged or disengaged.

AX-Relnotes: n/a.
Fixed: 1126923
Change-Id: I74cbf35c8e967aed2d7ece19378264aa1b6e9b0f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2419387
Commit-Queue: Anastasia Helfinstein <anastasi@google.com>
Reviewed-by: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809118}

chrome/browser/resources/chromeos/accessibility/switch_access/navigation_manager.js

@@ -32,6 +32,14 @@ class NavigationManager {
 
   // =============== Static Methods ==============
 
+  /**
+   * @param {!SAChildNode} node
+   * @return {boolean}
+   */
+  static currentGroupHasChild(node) {
+    return NavigationManager.instance.group_.children.includes(node);
+  }
+
   /**
    * Enters |this.node_|.
    */
@@ -50,8 +58,6 @@ class NavigationManager {
 
   /**
    * Puts focus on the virtual keyboard, if the current node is a text input.
-   * TODO(crbug/946190): Handle the case where the user has not enabled the
-   *     onscreen keyboard.
    */
   static enterKeyboard() {
     const navigator = NavigationManager.instance;

chrome/browser/resources/chromeos/accessibility/switch_access/nodes/keyboard_node.js

@@ -34,6 +34,23 @@ class KeyboardNode extends BasicNode {
     return false;
   }
 
+  /** @override */
+  isValidAndVisible() {
+    if (super.isValidAndVisible()) {
+      return true;
+    }
+    if (!KeyboardNode.resetting &&
+        NavigationManager.currentGroupHasChild(this)) {
+      // TODO(crbug/1130773): move this code to another location, if possible
+      KeyboardNode.resetting = true;
+      KeyboardRootNode.ignoreNextExit_ = true;
+      NavigationManager.exitKeyboard();
+      NavigationManager.enterKeyboard();
+    }
+
+    return false;
+  }
+
   /** @override */
   performAction(action) {
     if (action !== SwitchAccessMenuAction.SELECT) {
@@ -66,6 +83,7 @@ class KeyboardRootNode extends BasicRootNode {
    */
   constructor(groupNode) {
     super(groupNode);
+    KeyboardNode.resetting = false;
   }
 
   // ================= General methods =================
@@ -80,6 +98,11 @@ class KeyboardRootNode extends BasicRootNode {
 
   /** @override */
   onExit() {
+    if (KeyboardRootNode.ignoreNextExit_) {
+      KeyboardRootNode.ignoreNextExit_ = false;
+      return;
+    }
+
     // If the keyboard is currently visible, ignore the corresponding
     // state change.
     if (KeyboardRootNode.isVisible_) {