Use Ash's ShelfWindowWatcher for app panel windows.

ash/common/wm_window.h

 // Copyright 2016 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 ASH_COMMON_WM_WINDOW_H_
 #define ASH_COMMON_WM_WINDOW_H_
 
 #include <memory>
 #include <vector>
 
 #include "ash/ash_export.h"
 #include "base/strings/string16.h"
 #include "base/time/time.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/compositor/layer_animation_element.h"
+#include "ui/gfx/image/image_skia.h"
 #include "ui/wm/core/window_animations.h"
 #include "ui/wm/public/window_types.h"
 
 namespace display {
 class Display;
 }
 
 namespace gfx {
 class Point;
 class Rect;
@@ skipping 104 matching lines @@
   virtual gfx::Transform GetTargetTransform() const = 0;
 
   virtual bool IsSystemModal() const = 0;
 
   virtual bool GetBoolProperty(WmWindowProperty key) = 0;
   virtual SkColor GetColorProperty(WmWindowProperty key) = 0;
   virtual void SetColorProperty(WmWindowProperty key, SkColor value) = 0;
   virtual int GetIntProperty(WmWindowProperty key) = 0;
   virtual void SetIntProperty(WmWindowProperty key, int value) = 0;
 
+  virtual gfx::ImageSkia GetWindowIcon() = 0;
+  virtual gfx::ImageSkia GetAppIcon() = 0;
+
   wm::WindowState* GetWindowState() {
     return const_cast<wm::WindowState*>(
         const_cast<const WmWindow*>(this)->GetWindowState());
   }
   virtual const wm::WindowState* GetWindowState() const = 0;
 
   // The implementation of this matches aura::Window::GetToplevelWindow().
   virtual WmWindow* GetToplevelWindow() = 0;
   // The implementation of this matches
   // aura::client::ActivationClient::GetToplevelWindow().
@@ skipping 179 matching lines @@
   virtual void AddLimitedPreTargetHandler(ui::EventHandler* handler) = 0;
   virtual void RemoveLimitedPreTargetHandler(ui::EventHandler* handler) = 0;
 
  protected:
   virtual ~WmWindow() {}
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_WINDOW_H_