Revert of Added a system caret used for accessibility on Windows.

ui/accessibility/platform/ax_system_caret_win.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 UI_ACCESSIBILITY_PLATFORM_AX_SYSTEM_CARET_WIN_H_
-#define UI_ACCESSIBILITY_PLATFORM_AX_SYSTEM_CARET_WIN_H_
-
-#include <oleacc.h>
-
-#include "base/macros.h"
-#include "base/win/scoped_comptr.h"
-#include "ui/accessibility/ax_export.h"
-#include "ui/accessibility/ax_node_data.h"
-#include "ui/accessibility/ax_tree_data.h"
-#include "ui/accessibility/platform/ax_platform_node_delegate.h"
-#include "ui/gfx/geometry/rect.h"
-#include "ui/gfx/native_widget_types.h"
-
-namespace ui {
-
-class AXPlatformNodeWin;
-
-// A class representing the position of the caret to assistive software on
-// Windows. This is required because Chrome doesn't use the standard system
-// caret and because some assistive software still relies on specific
-// accessibility APIs to retrieve the caret position.
-class AX_EXPORT AXSystemCaretWin : private AXPlatformNodeDelegate {
- public:
-  explicit AXSystemCaretWin(gfx::AcceleratedWidget event_target);
-  virtual ~AXSystemCaretWin();
-
-  base::win::ScopedComPtr<IAccessible> GetCaret() const;
-  void MoveCaretTo(const gfx::Rect& bounds);
-
- private:
-  // |AXPlatformNodeDelegate| members.
-  const AXNodeData& GetData() const override;
-  const ui::AXTreeData& GetTreeData() const override;
-  gfx::NativeWindow GetTopLevelWidget() override;
-  gfx::NativeViewAccessible GetParent() override;
-  int GetChildCount() override;
-  gfx::NativeViewAccessible ChildAtIndex(int index) override;
-  gfx::Rect GetScreenBoundsRect() const override;
-  gfx::NativeViewAccessible HitTestSync(int x, int y) override;
-  gfx::NativeViewAccessible GetFocus() override;
-  gfx::AcceleratedWidget GetTargetForNativeAccessibilityEvent() override;
-  bool AccessibilityPerformAction(const ui::AXActionData& data) override;
-  bool ShouldIgnoreHoveredStateForTesting() override;
-
-  AXPlatformNodeWin* caret_;
-  gfx::AcceleratedWidget event_target_;
-  AXNodeData data_;
-
-  friend class AXPlatformNodeWin;
-  DISALLOW_COPY_AND_ASSIGN(AXSystemCaretWin);
-};
-
-}  // namespace ui
-
-#endif  // UI_ACCESSIBILITY_PLATFORM_AX_SYSTEM_CARET_WIN_H_