Keep track of accessibility focus across windows.

ui/views/accessibility/ax_aura_obj_cache.cc

Index: ui/views/accessibility/ax_aura_obj_cache.cc
diff --git a/ui/views/accessibility/ax_aura_obj_cache.cc b/ui/views/accessibility/ax_aura_obj_cache.cc
index 47964bee739a40487fc24c7fc673fcfd6ad6ac15..72abde71a028195511abdb3141eaa3d754a1cb58 100644
--- a/ui/views/accessibility/ax_aura_obj_cache.cc
+++ b/ui/views/accessibility/ax_aura_obj_cache.cc
@@ -6,6 +6,7 @@
 
 #include "base/memory/singleton.h"
 #include "base/stl_util.h"
+#include "ui/aura/client/focus_client.h"
 #include "ui/aura/window.h"
 #include "ui/views/accessibility/ax_aura_obj_wrapper.h"
 #include "ui/views/accessibility/ax_view_obj_wrapper.h"
@@ -30,6 +31,14 @@ AXAuraObjWrapper* AXAuraObjCache::GetOrCreate(Widget* widget) {
 }
 
 AXAuraObjWrapper* AXAuraObjCache::GetOrCreate(aura::Window* window) {
+  if (!focus_client_) {
+    aura::Window* root_window = window->GetRootWindow();
+    if (root_window) {
+      focus_client_ = aura::client::GetFocusClient(root_window);
+      if (focus_client_)
+        focus_client_->AddObserver(this);
+    }
+  }
   return CreateInternal<AXWindowObjWrapper>(window, window_to_id_map_);
 }
 
@@ -97,7 +106,17 @@ void AXAuraObjCache::GetTopLevelWindows(
   }
 }
 
-AXAuraObjCache::AXAuraObjCache() : current_id_(1), is_destroying_(false) {
+AXAuraObjWrapper* AXAuraObjCache::GetFocus() {
+  View* focused_view = GetFocusedView();
+  if (focused_view)
+    return GetOrCreate(focused_view);
+  return nullptr;
+}
+
+AXAuraObjCache::AXAuraObjCache()
+    : current_id_(1),
+      focus_client_(nullptr),
+      is_destroying_(false) {
 }
 
 AXAuraObjCache::~AXAuraObjCache() {
@@ -106,6 +125,40 @@ AXAuraObjCache::~AXAuraObjCache() {
   cache_.clear();
 }
 
+View* AXAuraObjCache::GetFocusedView() {
+  if (!focus_client_)
+    return nullptr;
+
+  aura::Window* focused_window = focus_client_->GetFocusedWindow();
+  if (!focused_window)
+    return nullptr;
+
+  Widget* focused_widget = Widget::GetWidgetForNativeView(focused_window);
+  while (!focused_widget) {
+    focused_window = focused_window->parent();
+    if (!focused_window)
+      break;
+
+    focused_widget = Widget::GetWidgetForNativeView(focused_window);
+  }
+
+  if (!focused_widget)
+    return nullptr;
+
+  FocusManager* focus_manager = focused_widget->GetFocusManager();
+  if (!focus_manager)
+    return nullptr;
+
+  return focus_manager->GetFocusedView();
+}
+
+void AXAuraObjCache::OnWindowFocused(aura::Window* gained_focus,
+                                     aura::Window* lost_focus) {
+  View* view = GetFocusedView();
+  if (view)
+    view->NotifyAccessibilityEvent(ui::AX_EVENT_FOCUS, true);
+}
+
 template <typename AuraViewWrapper, typename AuraView>
 AXAuraObjWrapper* AXAuraObjCache::CreateInternal(
     AuraView* aura_view,