views: Make view::Views::GetPreferredSize() const.

ui/views/window/native_frame_view.cc

 // Copyright (c) 2011 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 "ui/views/window/native_frame_view.h"
 
 #include "ui/views/widget/native_widget.h"
 #include "ui/views/widget/widget.h"
 
 #if defined(OS_WIN)
@@ skipping 49 matching lines @@
 }
 
 void NativeFrameView::UpdateWindowTitle() {
   // Nothing to do.
 }
 
 // Returns the client size. On Windows, this is the expected behavior for
 // native frames (see |NativeWidgetWin::WidgetSizeIsClientSize()|), while other
 // platforms currently always return client bounds from
 // |GetWindowBoundsForClientBounds()|.
-gfx::Size NativeFrameView::GetPreferredSize() {
+gfx::Size NativeFrameView::GetPreferredSize() const {
   return frame_->client_view()->GetPreferredSize();
 }
 
-gfx::Size NativeFrameView::GetMinimumSize() {
+gfx::Size NativeFrameView::GetMinimumSize() const {
   return frame_->client_view()->GetMinimumSize();
 }
 
 gfx::Size NativeFrameView::GetMaximumSize() {
   return frame_->client_view()->GetMaximumSize();
 }
 
 }  // namespace views