Added a class acting as a fake caret for accessibility.

content/browser/renderer_host/legacy_render_widget_host_win.h

Index: content/browser/renderer_host/legacy_render_widget_host_win.h
diff --git a/content/browser/renderer_host/legacy_render_widget_host_win.h b/content/browser/renderer_host/legacy_render_widget_host_win.h
index 398c633a69cca5fa2e6bf6398f6b0e4ad55510b6..91a02052432b235f8d5fe59cf65754cb08c81edd 100644
--- a/content/browser/renderer_host/legacy_render_widget_host_win.h
+++ b/content/browser/renderer_host/legacy_render_widget_host_win.h
@@ -24,6 +24,7 @@ class DirectManipulationHelper;
 }  // namespace gfx
 
 namespace ui {
+class AXFakeCaretWin;
 class WindowEventTarget;
 }
 
@@ -120,6 +121,9 @@ class CONTENT_EXPORT LegacyRenderWidgetHostHWND
     host_ = host;
   }
 
+  // Changes the position of the fake caret.
+  void MoveCaretTo(const gfx::Rect& bounds);
+
  protected:
   void OnFinalMessage(HWND hwnd) override;
 
@@ -159,6 +163,9 @@ class CONTENT_EXPORT LegacyRenderWidgetHostHWND
 
   RenderWidgetHostViewAura* host_;
 
+  // Some assistive software need to track the location of the caret.
+  std::unique_ptr<ui::AXFakeCaretWin> ax_fake_caret_;
+
   // This class provides functionality to register the legacy window as a
   // Direct Manipulation consumer. This allows us to support smooth scroll
   // in Chrome on Windows 10.