Keep track of accessibility focus across windows.

chrome/renderer/extensions/automation_internal_custom_bindings.cc

Index: chrome/renderer/extensions/automation_internal_custom_bindings.cc
diff --git a/chrome/renderer/extensions/automation_internal_custom_bindings.cc b/chrome/renderer/extensions/automation_internal_custom_bindings.cc
index 3a05d188a739a69f1cb5d5ffedf60d255fdde848..431a3823643b17454cde5d48e7fc75c57180b259 100644
--- a/chrome/renderer/extensions/automation_internal_custom_bindings.cc
+++ b/chrome/renderer/extensions/automation_internal_custom_bindings.cc
@@ -416,6 +416,7 @@ AutomationInternalCustomBindings::AutomationInternalCustomBindings(
   ROUTE_FUNCTION(AddTreeChangeObserver);
   ROUTE_FUNCTION(RemoveTreeChangeObserver);
   ROUTE_FUNCTION(GetChildIDAtIndex);
+  ROUTE_FUNCTION(GetFocus);
   #undef ROUTE_FUNCTION
 
   // Bindings that take a Tree ID and return a property of the tree.
@@ -777,6 +778,54 @@ void AutomationInternalCustomBindings::RemoveTreeChangeObserver(
   UpdateOverallTreeChangeObserverFilter();
 }
 
+void AutomationInternalCustomBindings::GetFocus(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+  if (args.Length() != 1 || !args[0]->IsNumber()) {
+    ThrowInvalidArgumentsException(this);
+    return;
+  }
+
+  int tree_id = args[0]->Int32Value();
+  ui::AXNode* focus = nullptr;
+  TreeCache* cache = GetTreeCacheFromTreeID(tree_id);
+  if (!cache)
+    return;
+
+  int focus_id = cache->tree.data().focus_id;
+  focus = cache->tree.GetFromId(focus_id);
+  if (!focus)
+    return;
+
+  while (focus->data().HasIntAttribute(ui::AX_ATTR_CHILD_TREE_ID)) {
+    // Try to keep following focus recursively, by letting |tree_id| be the
+    // new subtree to search in, while keeping |focus_tree_id| set to the tree
+    // where we know we found a focused node.
+    int child_tree_id =
+        focus->data().GetIntAttribute(ui::AX_ATTR_CHILD_TREE_ID);
+
+    TreeCache* child_cache = GetTreeCacheFromTreeID(child_tree_id);
+    if (!child_cache)
+      break;
+
+    int child_focus_id = child_cache->tree.data().focus_id;
+    ui::AXNode* child_focus = cache->tree.GetFromId(focus_id);
+    if (!child_focus)
+      break;
+
+    focus = child_focus;
+    tree_id = child_tree_id;
+    focus_id = child_focus_id;
+  }
+
+  v8::Isolate* isolate = GetIsolate();
+  v8::Local<v8::Object> result(v8::Object::New(isolate));
+  result->Set(CreateV8String(isolate, "treeId"),
+              v8::Integer::New(isolate, tree_id));
+  result->Set(CreateV8String(isolate, "nodeId"),
+              v8::Integer::New(isolate, focus_id));
+  args.GetReturnValue().Set(result);
+}
+
 void AutomationInternalCustomBindings::UpdateOverallTreeChangeObserverFilter() {
   tree_change_observer_overall_filter_ =
       api::automation::TREE_CHANGE_OBSERVER_FILTER_NOTREECHANGES;