Initial support for native accessibility in ARC

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

+// 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.
+
+#ifndef CHROME_BROWSER_CHROMEOS_ARC_ACCESSIBILITY_HELPER_AX_TREE_SOURCE_ARC_H_
+#define CHROME_BROWSER_CHROMEOS_ARC_ACCESSIBILITY_HELPER_AX_TREE_SOURCE_ARC_H_
+
+#include "components/exo/ax_tree_source_surface.h"

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

Is this file already landed? I've quickly checked your in-review CLs, but I
couldn't find this.

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

Nope not yet. Added!

+#include "components/exo/wm_helper.h"
+#include "ui/accessibility/ax_node.h"
+#include "ui/accessibility/ax_node_data.h"
+#include "ui/accessibility/ax_tree_data.h"
+
+namespace arc {
+
+// This class represents the accessibility tree from the focused ARC window.

[dmazzoni, 2017/01/19 19:48:16]

Just curious, why "the focused" ARC window? Could we have a separate tree source
for each ARC window, or will we swap out the same tree for whichever one is
focused?

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

I'm thinking we can reuse the same source tree for now.

+class AXTreeSourceArc : public exo::AXTreeSourceSurface,
+                        public exo::WMHelper::FocusObserver {
+ public:
+  // AXTreeSource overrides.
+  bool GetTreeData(ui::AXTreeData* data) const override;
+  ui::AXNode* GetRoot() const override;
+  ui::AXNode* GetFromId(int32_t id) const override;
+  int32_t GetId(ui::AXNode* node) const override;
+  void GetChildren(ui::AXNode* node,
+                   std::vector<ui::AXNode*>* out_children) const override;
+  ui::AXNode* GetParent(ui::AXNode* node) const override;
+  bool IsValid(ui::AXNode* node) const override;
+  bool IsEqual(ui::AXNode* node1, ui::AXNode* node2) const override;
+  ui::AXNode* GetNull() const override;
+  void SerializeNode(ui::AXNode* node, ui::AXNodeData* out_data) const override;
+
+ protected:
+  void Reset() override;
+
+  // exo::WMHelper::FocusObserver overrides.
+  void OnWindowFocused(aura::Window* gained_focus,
+                       aura::Window* lost_focus) override;
+};
+
+}  // namespace arc
+
+#endif  // CHROME_BROWSER_CHROMEOS_ARC_ACCESSIBILITY_HELPER_AX_TREE_SOURCE_ARC_H_