[Switch Access] Respond to locationChanged events

Bug: 1023035
Change-Id: Ie227ad87af4bba0cdb6f864e609b8b4103a2d603
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2001412
Commit-Queue: Anastasia Helfinstein <anastasi@google.com>
Reviewed-by: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732726}

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

@@ -120,6 +120,13 @@ class NavigationManager {
     this.setNode_(this.node_.next);
   }
 
+  /**
+   * Updates the focus ring locations in response to an automation event.
+   */
+  refreshFocusRings() {
+    this.focusRingManager_.setFocusNodes(this.node_, this.group_);
+  }
+
   /**
    * Selects the current node.
    */

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

@@ -20,6 +20,9 @@ class NodeWrapper extends SAChildNode {
 
     /** @private {boolean} */
     this.isGroup_ = SwitchAccessPredicate.isGroup(this.baseNode_, parent);
+
+    /** @private {function(chrome.automation.AutomationEvent)} */
+    this.locationChangedHandler_ = SwitchAccess.refreshFocusRings;
   }
 
   // ================= Getters and setters =================
@@ -117,6 +120,20 @@ class NodeWrapper extends SAChildNode {
     return SwitchAccessPredicate.isVisible(this.baseNode_);
   }
 
+  /** @override */
+  onFocus() {
+    this.baseNode_.addEventListener(
+        chrome.automation.EventType.LOCATION_CHANGED,
+        this.locationChangedHandler_, false /* is_capture */);
+  }
+
+  /** @override */
+  onUnfocus() {
+    this.baseNode_.removeEventListener(
+        chrome.automation.EventType.LOCATION_CHANGED,
+        this.locationChangedHandler_, false /* is_capture */);
+  }
+
   /** @override */
   performAction(action) {
     let ancestor;
@@ -191,6 +208,9 @@ class RootNodeWrapper extends SARootNode {
 
     /** @private {!AutomationNode} */
     this.baseNode_ = baseNode;
+
+    /** @private {function(chrome.automation.AutomationEvent)} */
+    this.locationChangedHandler_ = SwitchAccess.refreshFocusRings;
   }
 
   // ================= Getters and setters =================
@@ -234,6 +254,20 @@ class RootNodeWrapper extends SARootNode {
     return !!this.baseNode_.role && super.isValidGroup();
   }
 
+  /** @override */
+  onFocus() {
+    this.baseNode_.addEventListener(
+        chrome.automation.EventType.LOCATION_CHANGED,
+        this.locationChangedHandler_, false /* is_capture */);
+  }
+
+  /** @override */
+  onUnfocus() {
+    this.baseNode_.removeEventListener(
+        chrome.automation.EventType.LOCATION_CHANGED,
+        this.locationChangedHandler_, false /* is_capture */);
+  }
+
   // ================= Static methods =================
 
   /**

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

@@ -341,4 +341,11 @@ class SwitchAccess {
       return this.navigationManager_.getTreeForDebugging(wholeTree);
     }
   }
+
+  static refreshFocusRings() {
+    const switchAccess = SwitchAccess.get();
+    if (switchAccess.navigationManager_) {
+      switchAccess.navigationManager_.refreshFocusRings();
+    }
+  }
 }