Initial support for native accessibility in ARC

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

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/chromeos/arc/accessibility_helper/ax_tree_source_arc.h"
+
+#include "components/exo/shell_surface.h"
+#include "components/exo/surface.h"
+#include "ui/aura/window.h"
+
+namespace {
+
+exo::Surface* GetArcSurface(const aura::Window* window) {
+  exo::Surface* arc_surface = exo::Surface::AsSurface(window);
+  if (!arc_surface)
+    arc_surface = exo::ShellSurface::GetMainSurface(window);
+  return arc_surface;
+}
+
+}  // namespace
+
+namespace arc {
+
+bool AXTreeSourceArc::GetTreeData(ui::AXTreeData* data) const {
+  return false;
+}
+
+ui::AXNode* AXTreeSourceArc::GetRoot() const {
+  return nullptr;
+}
+
+ui::AXNode* AXTreeSourceArc::GetFromId(int32_t id) const {
+  return nullptr;
+}
+
+int32_t AXTreeSourceArc::GetId(ui::AXNode* node) const {
+  return -1;
+}
+
+void AXTreeSourceArc::GetChildren(
+    ui::AXNode* node,
+    std::vector<ui::AXNode*>* out_children) const {}
+
+ui::AXNode* AXTreeSourceArc::GetParent(ui::AXNode* node) const {
+  return nullptr;
+}
+
+bool AXTreeSourceArc::IsValid(ui::AXNode* node) const {
+  return false;
+}
+
+bool AXTreeSourceArc::IsEqual(ui::AXNode* node1, ui::AXNode* node2) const {
+  return false;
+}
+
+ui::AXNode* AXTreeSourceArc::GetNull() const {
+  return nullptr;
+}
+
+void AXTreeSourceArc::SerializeNode(ui::AXNode* node,
+                                    ui::AXNodeData* out_data) const {}
+
+void AXTreeSourceArc::Reset() {}
+
+void AXTreeSourceArc::OnWindowFocused(aura::Window* gained_focus,
+                                      aura::Window* lost_focus) {
+  if (gained_focus == lost_focus || !GetArcSurface(gained_focus))
+    return;
+
+  if (GetArcSurface(lost_focus)) {
+    exo::Surface* surface = GetArcSurface(lost_focus);
+    surface->set_ax_tree_source(nullptr);

[yawano, 2017/01/20 07:47:49]

Might we need to call AxTreeSourceArc::Reset here as this instance will be
reused for the gained focused window?

[David Tseng, 2017/01/20 23:00:56]

Done.

+  }
+
+  exo::Surface* focused_surface = GetArcSurface(gained_focus);

[yawano, 2017/01/20 07:47:49]

nit: how about to move this line at the first line of this method and avoid
calling GetArcSurface(gained_focus) 2 times?

[David Tseng, 2017/01/20 23:00:56]

Done.

+  focused_surface->set_ax_tree_source(this);
+}
+
+}  // namespace arc