Ignore focus events generated by Switch Access focus actions

When SA calls someAutomationNode.focus(), it may generate focus events on someAutomationNode later. This isn't always desirable, e.g. when the node is a text field and SA wants to remain on the VK.

Correct this by ignoring focus events of this type i.e. these events have eventFrom 'action'.

R=anastasi@google.com

Fixed: 1113669
AX-Relnotes: n/a
Change-Id: I2266f0aced57db1949dfad2793cc58ac2be923eb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2352613
Commit-Queue: David Tseng <dtseng@chromium.org>
Reviewed-by: Anastasia Helfinstein <anastasi@google.com>
Cr-Commit-Position: refs/heads/master@{#797836}

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

@@ -288,6 +288,11 @@ class NavigationManager {
    * @private
    */
   onFocusChange_(event) {
+    // Ignore focus changes from our own actions.
+    if (event.eventFrom == 'action') {
+      return;
+    }
+
     if (this.node_.isEquivalentTo(event.target)) {
       return;
     }