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 "ui/accessibility/ax_enums.h"
+#include "ui/accessibility/platform/ax_platform_node_win.h"
+#include "ui/gfx/geometry/rect_conversions.h"
+#include "ui/gfx/geometry/rect_f.h"
+
+namespace ui {
+
+AXFakeCaretWin::AXFakeCaretWin() {
+  caret_ = static_cast<AXPlatformNodeWin*>(AXPlatformNodeWin::Create(this));
+  data_.id = 0;
+  data_.role = AX_ROLE_DIV;

[dmazzoni, 2017/04/17 05:07:35]

We should create AX_ROLE_CARET and map it to ROLE_SYSTEM_CARET (yes, that is an
MSAA role)

+  data_.state = 0;
+  data_.SetName(L"caret");
+  data_.offset_container_id = -1;
+}
+
+AXFakeCaretWin::~AXFakeCaretWin() {
+  caret_->Destroy();
+  caret_ = nullptr;
+}
+
+base::win::ScopedComPtr<IAccessible> AXFakeCaretWin::GetCaret() const {
+  base::win::ScopedComPtr<IAccessible> caret_accessible;

[dmazzoni, 2017/04/17 05:07:35]

I don't think you need this. Just call caret_->GetNativeViewAccessible()

+  HRESULT hr = caret_->QueryInterface(
+      IID_IAccessible, reinterpret_cast<void**>(caret_accessible.Receive()));
+  DCHECK(SUCCEEDED(hr));
+  return caret_accessible;
+}
+
+void AXFakeCaretWin::SetBounds(gfx::Rect bounds) {
+  caret_->Lock();

[dmazzoni, 2017/04/17 05:07:35]

Why are you locking / unlocking? It's not clear where this is every used
anywhere other than the UI thread. If it is, the right solution is to post a
callback on the UI thread, not to lock (which may block and cause jank).

+  data_.location = gfx::RectF(bounds);
+  caret_->Unlock();
+}
+
+const AXNodeData& AXFakeCaretWin::GetData() const {
+  return data_;
+}
+
+gfx::NativeWindow AXFakeCaretWin::GetTopLevelWidget() {
+  return nullptr;
+}
+
+gfx::NativeViewAccessible AXFakeCaretWin::GetParent() {
+  return nullptr;
+}
+
+int AXFakeCaretWin::GetChildCount() {
+  return 0;
+}
+
+gfx::NativeViewAccessible AXFakeCaretWin::ChildAtIndex(int index) {
+  return nullptr;
+}
+
+gfx::Rect AXFakeCaretWin::GetScreenBoundsRect() const {
+  caret_->Lock();
+  gfx::Rect bounds = ToEnclosingRect(data_.location);
+  caret_->Unlock();
+  return bounds;
+}
+
+gfx::NativeViewAccessible AXFakeCaretWin::HitTestSync(int x, int y) {
+  return nullptr;
+}
+
+gfx::NativeViewAccessible AXFakeCaretWin::GetFocus() {
+  return nullptr;
+}
+
+gfx::AcceleratedWidget AXFakeCaretWin::GetTargetForNativeAccessibilityEvent() {
+  return gfx::kNullAcceleratedWidget;
+}
+
+bool AXFakeCaretWin::AccessibilityPerformAction(const ui::AXActionData& data) {
+  return false;
+}
+
+}  // namespace ui