[Switch Access] Refactor isGroup function to allow for changing values

In preparation for future changes, change the behavior of how Switch
Access checks if a child node is a group from initializing a field on
construction to implementing an abstract function.

Bug: None
Change-Id: I9a0657c19fcd7b3428ddfecb108d52a9cd0b2250
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1907192Reviewed-by: Aran Gilman <gilmanmh@google.com>
Commit-Queue: Anastasia Helfinstein <anastasi@google.com>
Cr-Commit-Position: refs/heads/master@{#713989}

chrome/browser/resources/chromeos/switch_access/nodes/back_button_node.js

@@ -10,7 +10,7 @@ class BackButtonNode extends SAChildNode {
    * @param {!SARootNode} group
    */
   constructor(group) {
-    super(false /* isGroup */);
+    super();
     /**
      * The group that the back button is shown for.
      * @private {!SARootNode}
@@ -65,6 +65,11 @@ class BackButtonNode extends SAChildNode {
     return this.node_ === node;
   }
 
+  /** @override */
+  isGroup() {
+    return false;
+  }
+
   /** @override */
   asRootNode() {
     return null;

chrome/browser/resources/chromeos/switch_access/nodes/group_node.js

@@ -15,7 +15,7 @@ class GroupNode extends SAChildNode {
    * @private
    */
   constructor(children) {
-    super(true /* isGroup */);
+    super();
 
     /** @type {!Array<!SAChildNode>} */
     this.children_ = children;
@@ -70,6 +70,11 @@ class GroupNode extends SAChildNode {
     return false;
   }
 
+  /** @override */
+  isGroup() {
+    return true;
+  }
+
   /** @override */
   asRootNode() {
     const root = new SARootNode();

chrome/browser/resources/chromeos/switch_access/nodes/node_wrapper.js

@@ -14,9 +14,12 @@ class NodeWrapper extends SAChildNode {
    * @param {?SARootNode} parent
    */
   constructor(baseNode, parent) {
-    super(SwitchAccessPredicate.isGroup(baseNode, parent));
+    super();
     /** @private {!AutomationNode} */
     this.baseNode_ = baseNode;
+
+    /** @private {boolean} */
+    this.isGroup_ = SwitchAccessPredicate.isGroup(this.baseNode_, parent);
   }
 
   /** @override */
@@ -138,6 +141,11 @@ class NodeWrapper extends SAChildNode {
     return this.baseNode_ === node;
   }
 
+  /** @override */
+  isGroup() {
+    return this.isGroup_;
+  }
+
   /** @override */
   asRootNode() {
     if (!this.isGroup()) {

chrome/browser/resources/chromeos/switch_access/nodes/switch_access_node.js

@@ -13,12 +13,7 @@
  * @abstract
  */
 class SAChildNode {
-  /**
-   * @param {boolean} isGroup
-   */
-  constructor(isGroup) {
-    this.isGroup_ = isGroup;
-
+  constructor() {
     /** @private {?SAChildNode} */
     this.previous_ = null;
 
@@ -71,10 +66,9 @@ class SAChildNode {
   /**
    * Returns whether this node should be displayed as a group.
    * @return {boolean}
+   * @abstract
    */
-  isGroup() {
-    return this.isGroup_;
-  }
+  isGroup() {}
 
   /**
    * Returns a list of all the actions available for this node.
@@ -159,7 +153,7 @@ class SAChildNode {
    * @return {string}
    */
   debugString(wholeTree, prefix = '', currentNode = null) {
-    if (this.isGroup_ && wholeTree) {
+    if (this.isGroup() && wholeTree) {
       return this.asRootNode().debugString(
           wholeTree, prefix + '  ', currentNode);
     }
@@ -176,7 +170,7 @@ class SAChildNode {
       str += 'loc(' + RectHelper.toString(loc) + ') ';
     }
 
-    if (this.isGroup_) {
+    if (this.isGroup()) {
       str += '[isGroup]';
     }