Added a class acting as a fake caret for accessibility.

ui/accessibility/platform/ax_fake_caret_win.h

+// Copyright (c) 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_FAKE_CARET_WIN_H_
+#define UI_ACCESSIBILITY_PLATFORM_AX_FAKE_CARET_WIN_H_
+
+#include <atlbase.h>
+#include <atlcom.h>
+#include <oleacc.h>
+#include <windows.h>
+
+#include "base/compiler_specific.h"
+#include "base/macros.h"
+#include "ui/accessibility/ax_export.h"
+#include "ui/gfx/geometry/rect.h"
+
+namespace ui {
+
+// 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 __declspec(uuid("170646b5-cb01-43e7-93f0-3ca455828d03")) AXFakeCaretWin
+    : NON_EXPORTED_BASE(public CComObjectRootEx<CComSingleThreadModel>),
+      public IDispatchImpl<IAccessible,
+                           &IID_IAccessible,
+                           &LIBID_Accessibility> {
+ public:
+  BEGIN_COM_MAP(AXFakeCaretWin)
+  COM_INTERFACE_ENTRY2(IDispatch, IAccessible)
+  COM_INTERFACE_ENTRY(IAccessible)
+  END_COM_MAP()
+
+  AXFakeCaretWin();
+  virtual ~AXFakeCaretWin() = default;
+
+  gfx::Rect bounds() { return bounds_; }
+  AX_EXPORT static void SetBounds(gfx::Rect bounds);
+
+  // IAccessible methods.
+
+  // Performs the default action on a given object.
+  STDMETHODIMP accDoDefaultAction(VARIANT var_id) override { return E_NOTIMPL; }
+
+  // Retrieves the child element or child object at a given point on the screen.
+  STDMETHODIMP accHitTest(LONG x_left, LONG y_top, VARIANT* child) override {
+    return E_NOTIMPL;
+  }
+
+  // Retrieves the specified object's current screen location.
+  STDMETHODIMP accLocation(LONG* x_left,
+                           LONG* y_top,
+                           LONG* width,
+                           LONG* height,
+                           VARIANT var_id) override;
+
+  // Traverses to another UI element and retrieves the object.
+  STDMETHODIMP accNavigate(LONG nav_dir, VARIANT start, VARIANT* end) override {
+    return E_NOTIMPL;
+  }
+
+  // Retrieves an IDispatch interface pointer for the specified child.
+  STDMETHODIMP get_accChild(VARIANT var_child,
+                            IDispatch** disp_child) override {
+    return E_NOTIMPL;
+  }
+
+  // Retrieves the number of accessible children.
+  STDMETHODIMP get_accChildCount(LONG* child_count) override {
+    return E_NOTIMPL;
+  }
+
+  // Retrieves a string that describes the object's default action.
+  STDMETHODIMP get_accDefaultAction(VARIANT var_id,
+                                    BSTR* default_action) override {
+    return E_NOTIMPL;
+  }
+
+  // Retrieves the object's description.
+  STDMETHODIMP get_accDescription(VARIANT var_id, BSTR* desc) override {
+    return E_NOTIMPL;
+  }
+
+  // Retrieves the object that has the keyboard focus.
+  STDMETHODIMP get_accFocus(VARIANT* focus_child) override { return E_NOTIMPL; }
+
+  // Retrieves the help information associated with the object.
+  STDMETHODIMP get_accHelp(VARIANT var_id, BSTR* heflp) override {
+    return E_NOTIMPL;
+  }
+
+  // Retrieves the specified object's shortcut.
+  STDMETHODIMP get_accKeyboardShortcut(VARIANT var_id,
+                                       BSTR* access_key) override {
+    return E_NOTIMPL;
+  }
+
+  // Retrieves the name of the specified object.
+  STDMETHODIMP get_accName(VARIANT var_id, BSTR* name) override;
+
+  // Retrieves the IDispatch interface of the object's parent.
+  STDMETHODIMP get_accParent(IDispatch** disp_parent) override {
+    return E_NOTIMPL;
+  }
+
+  // Retrieves information describing the role of the specified object.
+  STDMETHODIMP get_accRole(VARIANT var_id, VARIANT* role) override;
+
+  // Retrieves the current state of the specified object.
+  STDMETHODIMP get_accState(VARIANT var_id, VARIANT* state) override {
+    return E_NOTIMPL;
+  }
+
+  // Returns the value associated with the object.
+  STDMETHODIMP get_accValue(VARIANT var_id, BSTR* value) override {
+    return E_NOTIMPL;
+  }
+
+  // Make an object take focus or extend the selection.
+  STDMETHODIMP accSelect(LONG flags_sel, VARIANT var_id) override {
+    return E_NOTIMPL;
+  }
+
+  STDMETHODIMP get_accHelpTopic(BSTR* help_file,
+                                VARIANT var_id,
+                                LONG* topic_id) override {
+    return E_NOTIMPL;
+  }
+
+  STDMETHODIMP get_accSelection(VARIANT* selected) override {
+    return E_NOTIMPL;
+  }
+
+  // Deprecated methods.
+  STDMETHODIMP put_accName(VARIANT var_id, BSTR put_name) override {
+    return E_NOTIMPL;
+  }
+
+  STDMETHODIMP put_accValue(VARIANT var_id, BSTR put_val) override {
+    return E_NOTIMPL;
+  }
+
+ private:
+  const LPCTSTR OBJECT_NAME = L"Caret";
+  // There is only one caret present at any one time.
+  static gfx::Rect bounds_;
+  DISALLOW_COPY_AND_ASSIGN(AXFakeCaretWin);
+};
+
+}  // namespace ui
+
+#endif  // UI_ACCESSIBILITY_PLATFORM_AX_FAKE_CARET_WIN_H_