views: Also const-ify GetMaximumSize().

apps/ui/views/app_window_frame_view.cc

 // Copyright 2014 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 "apps/ui/views/app_window_frame_view.h"
 
 #include "apps/ui/native_app_window.h"
 #include "base/strings/utf_string_conversions.h"
 #include "extensions/common/draggable_region.h"
 #include "grit/theme_resources.h"
@@ skipping 315 matching lines @@
   min_size.Enlarge(0, client_bounds.y());
   // Ensure we have enough space for the window icon and buttons.  We allow
   // the title string to collapse to zero width.
   int closeButtonOffsetX = (kCaptionHeight - close_button_->height()) / 2;
   int header_width = close_button_->width() + closeButtonOffsetX * 2;
   if (header_width > min_size.width())
     min_size.set_width(header_width);
   return min_size;
 }
 
-gfx::Size AppWindowFrameView::GetMaximumSize() {
+gfx::Size AppWindowFrameView::GetMaximumSize() const {
   gfx::Size max_size = widget_->client_view()->GetMaximumSize();
 
   // Add to the client maximum size the height of any title bar and borders.
   gfx::Size client_size = GetBoundsForClientView().size();
   if (max_size.width())
     max_size.Enlarge(width() - client_size.width(), 0);
   if (max_size.height())
     max_size.Enlarge(0, height() - client_size.height());
 
   return max_size;
@@ skipping 44 matching lines @@
     restore_button_->SetImage(
         views::CustomButton::STATE_NORMAL,
         rb.GetNativeImageNamed(IDR_APP_WINDOW_RESTORE).ToImageSkia());
     minimize_button_->SetImage(
         views::CustomButton::STATE_NORMAL,
         rb.GetNativeImageNamed(IDR_APP_WINDOW_MINIMIZE).ToImageSkia());
   }
 }
 
 }  // namespace apps