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

ui/views/examples/scroll_view_example.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/examples/scroll_view_example.h"
 
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/views/background.h"
 #include "ui/views/controls/button/label_button.h"
 #include "ui/views/controls/button/radio_button.h"
 #include "ui/views/layout/grid_layout.h"
 #include "ui/views/view.h"
 
 using base::ASCIIToUTF16;
 
 namespace views {
 namespace examples {
 
 // ScrollView's content, which draws gradient color on background.
 // TODO(oshima): add child views as well.
 class ScrollViewExample::ScrollableView : public View {
  public:
   ScrollableView() {
     SetColor(SK_ColorRED, SK_ColorCYAN);
     AddChildView(new LabelButton(NULL, ASCIIToUTF16("Button")));
     AddChildView(new RadioButton(ASCIIToUTF16("Radio Button"), 0));
   }
 
-  virtual gfx::Size GetPreferredSize() OVERRIDE {
+  virtual gfx::Size GetPreferredSize() const OVERRIDE {
     return gfx::Size(width(), height());
   }
 
   void SetColor(SkColor from, SkColor to) {
     set_background(Background::CreateVerticalGradientBackground(from, to));
   }
 
   void PlaceChildY(int index, int y) {
     View* view = child_at(index);
     gfx::Size size = view->GetPreferredSize();
@@ skipping 67 matching lines @@
     scrollable_->SetColor(SK_ColorYELLOW, SK_ColorGREEN);
   } else if (sender == scroll_to_) {
     scroll_view_->contents()->ScrollRectToVisible(
         gfx::Rect(20, 500, 1000, 500));
   }
   scroll_view_->Layout();
 }
 
 }  // namespace examples
 }  // namespace views