Added a class acting as a fake caret for accessibility.

ui/accessibility/platform/ax_fake_caret_win.cc

+// 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.
+
+#include "ui/accessibility/platform/ax_fake_caret_win.h"
+
+#include <windows.h>
+
+#include "base/logging.h"
+#include "ui/accessibility/ax_enums.h"
+#include "ui/accessibility/platform/ax_platform_node_win.h"
+#include "ui/accessibility/platform/ax_platform_unique_id.h"
+#include "ui/gfx/geometry/rect_conversions.h"
+#include "ui/gfx/geometry/rect_f.h"
+
+namespace {
+
+base::LazyInstance<ui::AXFakeCaretWin>::Leaky g_ax_fake_caret_win =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+namespace ui {
+
+AXFakeCaretWin::AXFakeCaretWin() : event_target_(gfx::kNullAcceleratedWidget) {
+  caret_ = static_cast<AXPlatformNodeWin*>(AXPlatformNodeWin::Create(this));
+  data_.id = GetNextAXPlatformNodeUniqueId();
+  data_.role = AX_ROLE_CARET;
+  data_.state = 0;
+  data_.SetName(L"caret");
+  data_.offset_container_id = -1;
+}
+
+AXFakeCaretWin::~AXFakeCaretWin() {
+  caret_->Destroy();
+  caret_ = nullptr;
+}
+
+// static
+AXFakeCaretWin* AXFakeCaretWin::Get() {
+  return g_ax_fake_caret_win.Pointer();
+}
+
+base::win::ScopedComPtr<IAccessible> AXFakeCaretWin::GetCaret() const {
+  base::win::ScopedComPtr<IAccessible> caret_accessible;
+  HRESULT hr = caret_->QueryInterface(
+      IID_IAccessible, reinterpret_cast<void**>(caret_accessible.Receive()));
+  DCHECK(SUCCEEDED(hr));
+  return caret_accessible;
+}
+
+void AXFakeCaretWin::MoveCaretTo(gfx::Rect bounds) {
+  data_.location = gfx::RectF(bounds);
+  if (event_target_) {
+    ::NotifyWinEvent(EVENT_OBJECT_LOCATIONCHANGE, event_target_, OBJID_CARET,
+                     -data_.id);
+  }
+}
+
+void AXFakeCaretWin::SetTargetForNativeAccessibilityEvent(
+    gfx::AcceleratedWidget event_target) {
+  event_target_ = event_target;

[dmazzoni, 2017/04/21 21:06:30]

So yeah, my suggestion would be that rather than making it a
singleton, each HWND would own one and it'd pass the
gfx::AcceleratedWidget in the constructor. I think that
would make lifetime management easier.

I think that would also make the Views implementation easy,
I think the caret could be owned by native_widget_win.

+}
+
+const AXNodeData& AXFakeCaretWin::GetData() const {
+  return data_;
+}
+
+gfx::NativeWindow AXFakeCaretWin::GetTopLevelWidget() {
+  return nullptr;
+}
+
+gfx::NativeViewAccessible AXFakeCaretWin::GetParent() {
+  if (!event_target_)
+    return nullptr;
+
+  gfx::NativeViewAccessible parent;
+  HRESULT hr =
+      ::AccessibleObjectFromWindow(event_target_, OBJID_WINDOW, IID_IAccessible,
+                                   reinterpret_cast<void**>(&parent));
+  if (SUCCEEDED(hr))
+    return parent;
+  return nullptr;
+}
+
+int AXFakeCaretWin::GetChildCount() {
+  return 0;
+}
+
+gfx::NativeViewAccessible AXFakeCaretWin::ChildAtIndex(int index) {
+  return nullptr;
+}
+
+gfx::Rect AXFakeCaretWin::GetScreenBoundsRect() const {
+  gfx::Rect bounds = ToEnclosingRect(data_.location);
+  return bounds;
+}
+
+gfx::NativeViewAccessible AXFakeCaretWin::HitTestSync(int x, int y) {
+  return nullptr;
+}
+
+gfx::NativeViewAccessible AXFakeCaretWin::GetFocus() {
+  return nullptr;
+}
+
+gfx::AcceleratedWidget AXFakeCaretWin::GetTargetForNativeAccessibilityEvent() {
+  return event_target_;
+}
+
+bool AXFakeCaretWin::AccessibilityPerformAction(const ui::AXActionData& data) {
+  return false;
+}
+
+}  // namespace ui