Map focusable state

- some Android apps require focusable nodes have either focus or
  makeVisible actions performed on them for some UI to show up
  (e.g. Assistant)

- ChromeVox, as a result, needs to observe more containers. For
  focusable nodes, ChromeVox will not typically descend into their
  descendants unless the node's role is explicitly known to be a
  container. In Android, this is mostly nodes with role 'list'.

their contents shown Navigate in other apps with many focusable
containers e.g. Play Store. Verify navigation continues into
descendants.

Test: navigate in Assistant. Verify that invisible listItem nodes have
Bug: 788650
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I3a6b512b3d133f6bae9e89dd11488229c0fe4660
Reviewed-on: https://chromium-review.googlesource.com/792098Reviewed-by: Yuki Awano <yawano@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519813}

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

@@ -253,9 +253,8 @@ void PopulateAXState(arc::mojom::AccessibilityNodeInfoData* node,
   // These mappings were taken from accessibility utils (Android -> Chrome) and
   // BrowserAccessibilityAndroid. They do not completely match the above two
   // sources.
-  // The FOCUSABLE state is not mapped because Android places focusability on
-  // many ancestor nodes.
   MAP_STATE(AXBooleanProperty::EDITABLE, ui::AX_STATE_EDITABLE);
+  MAP_STATE(AXBooleanProperty::FOCUSABLE, ui::AX_STATE_FOCUSABLE);
   MAP_STATE(AXBooleanProperty::MULTI_LINE, ui::AX_STATE_MULTILINE);
   MAP_STATE(AXBooleanProperty::PASSWORD, ui::AX_STATE_PROTECTED);
   MAP_STATE(AXBooleanProperty::SELECTED, ui::AX_STATE_SELECTED);

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

@@ -265,8 +265,8 @@ AutomationPredicate.linebreak = function(first, second) {
 AutomationPredicate.container = function(node) {
   return AutomationPredicate.match({
     anyRole: [
-      Role.GENERIC_CONTAINER, Role.DOCUMENT, Role.GROUP, Role.LIST_ITEM,
-      Role.TOOLBAR, Role.WINDOW
+      Role.GENERIC_CONTAINER, Role.DOCUMENT, Role.GROUP, Role.LIST,
+      Role.LIST_ITEM, Role.TOOLBAR, Role.WINDOW
     ],
     anyPredicate: [
       AutomationPredicate.landmark, AutomationPredicate.structuralContainer,