Plumb through isImportantForAccessibility==false as ax::mojom::Role::kIgnored

In Android, accessibility services can respect the |isImportantForAccessibility| property.

Chrome-side, this best matches the concept of an ignored role.

In particular, this means, during linear navigation, a service should ignored this node while looking for the next directed node to visit.

Note that this should have no impact on descendants, unless, of course, they also have isImportantForAccessibility set to false.

Bug: 889074
Change-Id: I33ace3fc1e88450a9d2ce3798bd92feed2e08a19
Reviewed-on: https://chromium-review.googlesource.com/1243486Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594130}

chrome/browser/chromeos/arc/accessibility/ax_tree_source_arc.cc

@@ -632,6 +632,11 @@ void AXTreeSourceArc::PopulateAXRole(AXNodeInfoData* node,
                                  class_name);
   }
 
+  if (!GetProperty(node, AXBooleanProperty::IMPORTANCE)) {
+    out_data->role = ax::mojom::Role::kIgnored;
+    return;
+  }
+
   if (GetProperty(node, AXBooleanProperty::EDITABLE)) {
     out_data->role = ax::mojom::Role::kTextField;
     return;

chrome/browser/resources/chromeos/chromevox/cvox2/background/automation_predicate.js

@@ -355,7 +355,7 @@ AutomationPredicate.container = function(node) {
 AutomationPredicate.structuralContainer = AutomationPredicate.roles([
   Role.ALERT_DIALOG, Role.CLIENT, Role.DIALOG, Role.ROOT_WEB_AREA,
   Role.WEB_VIEW, Role.WINDOW, Role.EMBEDDED_OBJECT, Role.IFRAME,
-  Role.IFRAME_PRESENTATIONAL, Role.UNKNOWN
+  Role.IFRAME_PRESENTATIONAL, Role.IGNORED, Role.UNKNOWN
 ]);
 
 /**