Clean up and improve performance of findNodeMatchingPredicate.

Uses automation 'find' function and also only searches
changed subtrees after the initial search. This seems to improve
performance ~4x of the back button and menu, noticeable when
autoscan is on and set to high scanning speeds.

4x improvement measured on a webpage with a lot of nodes using
devtools 'performance' tab:
Before: Just under 4000ms on the back button moveForward call on
en.wikipedia.org/wiki/cat
After: Just under 1000ms on the back button moveForward call on
en.wikipedia.org/wiki/cat.

AX-Relnotes: N/A
Bug: 1108619
Change-Id: I9bd4bb1b92cde455949558c621700a6b900f2579
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2324118Reviewed-by: Anastasia Helfinstein <anastasi@google.com>
Reviewed-by: Jenny Zhang <jennyz@chromium.org>
Commit-Queue: Katie Dektar <katie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792459}

ash/system/accessibility/switch_access_back_button_view.cc

@@ -26,7 +26,6 @@ constexpr int kFocusRingSingleColorWidthDp = 2;
 // Additional buffer needed to prevent clipping at the focus ring's edges.
 constexpr int kFocusRingBufferDp = 1;
 
-constexpr char kUniqueId[] = "switch_access_back_button";
 constexpr int kRadiusDp = 18;
 }  // namespace
 
@@ -77,7 +76,6 @@ void SwitchAccessBackButtonView::ButtonPressed(views::Button* sender,
 void SwitchAccessBackButtonView::GetAccessibleNodeData(
     ui::AXNodeData* node_data) {
   node_data->role = ax::mojom::Role::kButton;
-  node_data->html_attributes.push_back(std::make_pair("id", kUniqueId));
 }
 
 int SwitchAccessBackButtonView::GetHeightForWidth(int w) const {

ash/system/accessibility/switch_access_menu_view.cc

@@ -19,7 +19,6 @@
 namespace ash {
 
 namespace {
-constexpr char kUniqueId[] = "switch_access_menu_view";
 constexpr int kMaxColumns = 3;
 
 struct ButtonInfo {
@@ -129,7 +128,6 @@ int SwitchAccessMenuView::GetBubbleWidthDip() const {
 
 void SwitchAccessMenuView::GetAccessibleNodeData(ui::AXNodeData* node_data) {
   node_data->role = ax::mojom::Role::kMenu;
-  node_data->html_attributes.push_back(std::make_pair("id", kUniqueId));
 }
 
 const char* SwitchAccessMenuView::GetClassName() const {

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

@@ -102,17 +102,6 @@ class MenuManager {
     MenuManager.instance.refreshActions_();
   }
 
-  /**
-   * Checks if the given node is the Switch Access menu node.
-   * @param {AutomationNode} node
-   * @return {boolean}
-   * @private
-   */
-  static isSwitchAccessMenuNode_(node) {
-    return !!node && node.role === chrome.automation.RoleType.MENU &&
-        node.htmlAttributes.id === 'switch_access_menu_view';
-  }
-
   // ================= Private Methods ==================
 
   /**
@@ -165,8 +154,11 @@ class MenuManager {
     if (this.hasValidMenuAutomationNode_() && this.menuAutomationNode_) {
       this.jumpToMenuAutomationNode_(this.menuAutomationNode_);
     }
-    SwitchAccess.findNodeMatchingPredicate(
-        MenuManager.isSwitchAccessMenuNode_,
+    SwitchAccess.findNodeMatching(
+        {
+          role: chrome.automation.RoleType.MENU,
+          attributes: {className: 'SwitchAccessMenuView'}
+        },
         this.jumpToMenuAutomationNode_.bind(this));
   }
 

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

@@ -135,18 +135,12 @@ class BackButtonNode extends SAChildNode {
     if (BackButtonNode.automationNode_ && BackButtonNode.automationNode_.role) {
       return;
     }
-    SwitchAccess.findNodeMatchingPredicate(
-        BackButtonNode.isBackButton_, BackButtonNode.saveAutomationNode_);
-  }
-
-  /**
-   * Checks if the given node is the back button automation node.
-   * @param {!AutomationNode} node
-   * @return {boolean}
-   * @private
-   */
-  static isBackButton_(node) {
-    return node.htmlAttributes.id === 'switch_access_back_button';
+    SwitchAccess.findNodeMatching(
+        {
+          role: chrome.automation.RoleType.BUTTON,
+          attributes: {className: 'SwitchAccessBackButtonView'}
+        },
+        BackButtonNode.saveAutomationNode_);
   }
 
   /**

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

@@ -118,9 +118,9 @@ class KeyboardRootNode extends RootNodeWrapper {
   static startWatchingVisibility() {
     const keyboardObject = KeyboardRootNode.getKeyboardObject();
     if (!keyboardObject) {
-      const isKeyboard = (n) => n.role === chrome.automation.RoleType.KEYBOARD;
-      SwitchAccess.findNodeMatchingPredicate(
-          isKeyboard, KeyboardRootNode.startWatchingVisibility);
+      SwitchAccess.findNodeMatching(
+          {role: chrome.automation.RoleType.KEYBOARD},
+          KeyboardRootNode.startWatchingVisibility);
       return;
     }
 

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

@@ -47,26 +47,24 @@ class SwitchAccess {
   }
 
   /**
-   * Helper function to robustly find a node fitting a given predicate, even if
+   * Helper function to robustly find a node fitting a given FindParams, even if
    * that node has not yet been created.
    * Used to find the menu and back button.
-   * @param {!function(!AutomationNode): boolean} predicate
+   * @param {!chrome.automation.FindParams} findParams
    * @param {!function(!AutomationNode): void} foundCallback
    */
-  static findNodeMatchingPredicate(predicate, foundCallback) {
+  static findNodeMatching(findParams, foundCallback) {
     const desktop = NavigationManager.desktopNode;
     // First, check if the node is currently in the tree.
-    const treeWalker = new AutomationTreeWalker(
-        desktop, constants.Dir.FORWARD, {visit: predicate});
-    treeWalker.next();
-    if (treeWalker.node) {
-      foundCallback(treeWalker.node);
+    let node = desktop.find(findParams);
+    if (node) {
+      foundCallback(node);
       return;
     }
     // If it's not currently in the tree, listen for changes to the desktop
     // tree.
     const onDesktopChildrenChanged = (event) => {
-      if (predicate(event.target)) {
+      if (event.target.matches(findParams)) {
         // If the event target is the node we're looking for, we've found it.
         desktop.removeEventListener(
             chrome.automation.EventType.CHILDREN_CHANGED,
@@ -74,15 +72,12 @@ class SwitchAccess {
         foundCallback(event.target);
       } else if (event.target.children.length > 0) {
         // Otherwise, see if one of its children is the node we're looking for.
-        const treeWalker = new AutomationTreeWalker(
-            event.target, constants.Dir.FORWARD,
-            {visit: predicate, root: (node) => node == event.target});
-        treeWalker.next();
-        if (treeWalker.node) {
+        node = event.target.find(findParams);
+        if (node) {
           desktop.removeEventListener(
               chrome.automation.EventType.CHILDREN_CHANGED,
               onDesktopChildrenChanged, false);
-          foundCallback(treeWalker.node);
+          foundCallback(node);
         }
       }
     };