Creates AXPosition to uniquely identify a position in the accessibility tree

content/browser/accessibility/ax_platform_position.h

+// Copyright 2016 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 CONTENT_BROWSER_ACCESSIBILITY_AX_PLATFORM_POSITION_H_
+#define CONTENT_BROWSER_ACCESSIBILITY_AX_PLATFORM_POSITION_H_
+
+#include <stdint.h>
+
+#include "content/browser/accessibility/ax_tree_id_registry.h"
+#include "content/browser/accessibility/browser_accessibility.h"
+#include "content/browser/accessibility/browser_accessibility_manager.h"
+#include "ui/accessibility/ax_node.h"
+#include "ui/accessibility/ax_position.h"
+
+namespace content {
+
+class AXPlatformPosition : AXPosition {
+ public:
+  ~AXPlatformPosition() override;
+
+  ui::AXTextAffinity get_affinity() { return affinity_; }

[dmazzoni, 2016/10/03 18:22:51]

I think this needs to be part of AXPosition.

It won't be possible to implement something like GetStartOfLine or GetEndOfLine
correctly if you don't have affinity in AXPosition.

+  void set_affinity(ui::AXTextAffinity affinity) { affinity_ = affinity; }
+
+ protected:
+  AXPlatformPosition(AXTreeIDRegistry::AXTreeID tree_id, int32_t anchor_id, int child_index, int text_offset, AXPositionType type);
+
+  BrowserAccessibility* GetPlatformNodeInTree(AXTreeIDRegistry::AXTreeID tree_id, int32-t node_id) const;
+  AXNode* GetNodeInTree(AXTreeIDRegistry::AXTreeID tree_id, int32-t node_id) const override;
+  int MaxTextOffset() const override;
+
+ private:
+  // TODO(nektar): Get rid of affinity and make Blink handle affinity internally.
+  ui::AXTextAffinity affinity;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_ACCESSIBILITY_AX_PLATFORM_POSITION_H_