Added a system caret used for accessibility on Windows.

ui/views/win/hwnd_message_handler_delegate.h

 // Copyright (c) 2012 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.
 
 #ifndef UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_DELEGATE_H_
 #define UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_DELEGATE_H_
 
 #include "ui/views/views_export.h"
 
 namespace gfx {
 class Insets;
 class Path;
 class Point;
 class Size;
 }
 
 namespace ui {
 class Accelerator;
+class InputMethodObserver;
 class KeyEvent;
 class MouseEvent;
 class TouchEvent;
 }
 
 namespace views {
 
 enum class FrameMode {
   SYSTEM_DRAWN,              // "glass" frame
   SYSTEM_DRAWN_NO_CONTROLS,  // "glass" frame but with custom window controls
   CUSTOM_DRAWN               // "opaque" frame
 };
 
 // Implemented by the object that uses the HWNDMessageHandler to handle
 // notifications from the underlying HWND and service requests for data.
 class VIEWS_EXPORT HWNDMessageHandlerDelegate {
  public:
+  // For tracking the caret for accessibility.
+  virtual void AddInputMethodObserver(ui::InputMethodObserver& observer) = 0;
+  virtual void RemoveInputMethodObserver(ui::InputMethodObserver& observer) = 0;
+
   // True if the widget associated with this window has a non-client view.
   virtual bool HasNonClientView() const = 0;
 
   // Returns who we want to be drawing the frame. Either the system (Windows)
   // will handle it or Chrome will custom draw it.
   virtual FrameMode GetFrameMode() const = 0;
 
   // True if a frame should be drawn. This will return true for some windows
   // that don't have a visible frame. Those usually have the WS_POPUP style, for
   // which Windows will remove the frame automatically if the frame mode is
@@ skipping 199 matching lines @@
   // Called when the window scale factor has changed.
   virtual void HandleWindowScaleFactorChanged(float window_scale_factor) = 0;
 
  protected:
   virtual ~HWNDMessageHandlerDelegate() {}
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_DELEGATE_H_