Added a system caret used for accessibility on Windows.

ui/views/widget/desktop_aura/desktop_window_tree_host_win.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_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_WIN_H_
 #define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_WIN_H_
 
 #include "base/macros.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/views/views_export.h"
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host.h"
 #include "ui/views/win/hwnd_message_handler_delegate.h"
 #include "ui/wm/public/animation_host.h"
 
 namespace aura {
 namespace client {
 class DragDropClient;
 class FocusClient;
 class ScopedTooltipDisabler;
 }
 }
 
+namespace ui {
+class InputMethodObserver;
+}  // namespace ui
+
 namespace views {
 class DesktopDragDropClientWin;
 class HWNDMessageHandler;
 class NonClientFrameView;
 
 namespace corewm {
 class TooltipWin;
 }
 
 class VIEWS_EXPORT DesktopWindowTreeHostWin
@@ skipping 92 matching lines @@
   void MoveCursorToScreenLocationInPixels(
       const gfx::Point& location_in_pixels) override;
 
   // Overridden from aura::client::AnimationHost
   void SetHostTransitionOffsets(
       const gfx::Vector2d& top_left_delta,
       const gfx::Vector2d& bottom_right_delta) override;
   void OnWindowHidingAnimationCompleted() override;
 
   // Overridden from HWNDMessageHandlerDelegate:
+  void AddInputMethodObserver(ui::InputMethodObserver& observer) override;
+  void RemoveInputMethodObserver(ui::InputMethodObserver& observer) override;
   bool HasNonClientView() const override;
   FrameMode GetFrameMode() const override;
   bool HasFrame() const override;
   void SchedulePaint() override;
   void SetAlwaysRenderAsActive(bool always_render_as_active) override;
   bool IsAlwaysRenderAsActive() override;
   bool CanResize() const override;
   bool CanMaximize() const override;
   bool CanMinimize() const override;
   bool CanActivate() const override;
@@ skipping 126 matching lines @@
   // Indicates if current window will receive mouse events when should not
   // become activated.
   bool wants_mouse_events_when_inactive_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopWindowTreeHostWin);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_WIN_H_