Support clickable boolean property for ARC++

 Test: manually click (with ChromeVox using Search+Space) ARC++ notification; verify app opens.
Bug: 786981

Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I6809ff0371e5315e0fe6aaf01e9c567215c77fc4
Reviewed-on: https://chromium-review.googlesource.com/783669
Commit-Queue: David Tseng <dtseng@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519532}

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

@@ -501,6 +501,10 @@ void AXTreeSourceArc::SerializeNode(mojom::AccessibilityNodeInfoData* node,
           node, arc::mojom::AccessibilityBooleanProperty::SCROLLABLE)) {
     out_data->AddBoolAttribute(ui::AX_ATTR_SCROLLABLE, true);
   }
+  if (GetBooleanProperty(node,
+                         arc::mojom::AccessibilityBooleanProperty::CLICKABLE)) {
+    out_data->AddBoolAttribute(ui::AX_ATTR_CLICKABLE, true);
+  }
 
   exo::WMHelper* wm_helper =
       exo::WMHelper::HasInstance() ? exo::WMHelper::GetInstance() : nullptr;

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

@@ -477,7 +477,11 @@ CommandHandler.onCommand = function(command) {
           ChromeVoxState.instance.navigateToRange(
               cursors.Range.fromNode(actionNode.inPageLinkTarget));
         } else {
-          actionNode.doDefault();
+          // Scan for a clickable, which overrides the |actionNode|.
+          var clickable = actionNode;
+          while (clickable && !clickable.clickable)
+            clickable = clickable.parent;
+          clickable ? clickable.doDefault() : actionNode.doDefault();
         }
       }
       // Skip all other processing; if focus changes, we should get an event

chrome/renderer/resources/extensions/automation/automation_node.js

@@ -822,6 +822,7 @@ var stringAttributes = [
 
 var boolAttributes = [
     'busy',
+    'clickable',
     'containerLiveAtomic',
     'containerLiveBusy',
     'liveAtomic',

ui/accessibility/ax_enums.idl

@@ -495,7 +495,10 @@
     canvas_has_fallback,
 
     // Indicates this node is scrollable (Android only).
-    scrollable
+    scrollable,
+
+    // A hint to clients that the node is clickable.
+    clickable
   };
 
   [cpp_enum_prefix_override="ax_attr"] enum AXIntListAttribute {

ui/accessibility/ax_node_data.cc

@@ -943,6 +943,9 @@ std::string AXNodeData::ToString() const {
       case AX_ATTR_SCROLLABLE:
         result += " scrollable=" + value;
         break;
+      case AX_ATTR_CLICKABLE:
+        result += " clickable=" + value;
+        break;
       case AX_BOOL_ATTRIBUTE_NONE:
         break;
     }