Add CanMinimize to classes that implement WidgetDelegate::CanMaximize.

ash/shell/panel_window.cc

 // 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.
 
 #include "ash/shell/panel_window.h"
 
 #include "ash/screen_util.h"
 #include "ash/shell.h"
 #include "ash/wm/panels/panel_frame_view.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 63 matching lines @@
 }
 
 bool PanelWindow::CanResize() const {
   return true;
 }
 
 bool PanelWindow::CanMaximize() const {
   return false;
 }
 
+bool PanelWindow::CanMinimize() const {
+  return false;
+}
+
 views::NonClientFrameView* PanelWindow::CreateNonClientFrameView(
     views::Widget* widget) {
   return new PanelFrameView(widget, PanelFrameView::FRAME_NONE);
 }
 
 }  // namespace ash