Added a class acting as a fake caret for accessibility.

ui/views/win/hwnd_message_handler_delegate.h

Index: ui/views/win/hwnd_message_handler_delegate.h
diff --git a/ui/views/win/hwnd_message_handler_delegate.h b/ui/views/win/hwnd_message_handler_delegate.h
index f5328c49e708efc084432f2be569f2f58ca99573..925dabbc265a2c0883345238b05d5827f51881c8 100644
--- a/ui/views/win/hwnd_message_handler_delegate.h
+++ b/ui/views/win/hwnd_message_handler_delegate.h
@@ -33,6 +33,10 @@ enum class FrameMode {
 // notifications from the underlying HWND and service requests for data.
 class VIEWS_EXPORT HWNDMessageHandlerDelegate {
  public:
+  // For tracking the caret for accessibility.
+  virtual void AddInputMethodObserver() const = 0;
+  virtual void RemoveInputMethodObserver() const = 0;
+
   // True if the widget associated with this window has a non-client view.
   virtual bool HasNonClientView() const = 0;