Added a system caret used for accessibility on Windows.

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index db539cc28d70af92c2836b80831452ff0fde2b9c..61b60b05345b9f7bc3b334c2517a143d09559918 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -885,7 +885,7 @@ void RenderWidgetHostViewAura::UpdateMouseLockRegion() {
 }
 
 void RenderWidgetHostViewAura::OnLegacyWindowDestroyed() {
-  legacy_render_widget_host_HWND_ = nullptr;
+  legacy_render_widget_host_HWND_ = NULL;
   legacy_window_destroyed_ = true;
 }
 #endif
@@ -2333,6 +2333,7 @@ void RenderWidgetHostViewAura::OnSelectionBoundsChanged(
 void RenderWidgetHostViewAura::OnTextSelectionChanged(
     TextInputManager* text_input_manager,
     RenderWidgetHostViewBase* updated_view) {
+#if defined(USE_X11) && !defined(OS_CHROMEOS)
   if (!GetTextInputManager())
     return;
 
@@ -2349,7 +2350,6 @@ void RenderWidgetHostViewAura::OnTextSelectionChanged(
   if (!focused_view)
     return;
 
-#if defined(USE_X11) && !defined(OS_CHROMEOS)
   const TextInputManager::TextSelection* selection =
       GetTextInputManager()->GetTextSelection(focused_view);
   if (selection->selected_text().length()) {
@@ -2357,24 +2357,7 @@ void RenderWidgetHostViewAura::OnTextSelectionChanged(
     ui::ScopedClipboardWriter clipboard_writer(ui::CLIPBOARD_TYPE_SELECTION);
     clipboard_writer.WriteText(selection->selected_text());
   }
-
-// #endif defined(USE_X11) && !defined(OS_CHROMEOS)
-#elif defined(OS_WIN)
-  // Some assistive software need to track the location of the caret.
-  if (!GetRenderWidgetHost() || !legacy_render_widget_host_HWND_)
-    return;
-
-  // Not using |GetCaretBounds| because it includes the whole of the selection,
-  // not just the focus.
-  const TextInputManager::SelectionRegion* region =
-      GetTextInputManager()->GetSelectionRegion(focused_view);
-  if (!region)
-    return;
-  const gfx::Rect caret_rect = ConvertRectToScreen(gfx::Rect(
-      region->focus.edge_top_rounded().x(),
-      region->focus.edge_top_rounded().y(), 1, region->focus.GetHeight()));
-  legacy_render_widget_host_HWND_->MoveCaretTo(caret_rect);
-#endif  // defined(OS_WIN)
+#endif  // defined(USE_X11) && !defined(OS_CHROMEOS)
 }
 
 void RenderWidgetHostViewAura::SetPopupChild(