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

ui/views/controls/button/image_button.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 "ui/views/controls/button/image_button.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "ui/accessibility/ax_view_state.h"
 #include "ui/gfx/animation/throb_animation.h"
 #include "ui/gfx/canvas.h"
@@ skipping 56 matching lines @@
   SchedulePaint();
 }
 
 void ImageButton::SetFocusPainter(scoped_ptr<Painter> focus_painter) {
   focus_painter_ = focus_painter.Pass();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // ImageButton, View overrides:
 
-gfx::Size ImageButton::GetPreferredSize() {
+gfx::Size ImageButton::GetPreferredSize() const {
   gfx::Size size = preferred_size_;
   if (!images_[STATE_NORMAL].isNull()) {
     size = gfx::Size(images_[STATE_NORMAL].width(),
                      images_[STATE_NORMAL].height());
   }
 
   gfx::Insets insets = GetInsets();
   size.Enlarge(insets.width(), insets.height());
   return size;
 }
@@ skipping 157 matching lines @@
   *tooltip = toggled_tooltip_text_;
   return true;
 }
 
 void ToggleImageButton::GetAccessibleState(ui::AXViewState* state) {
   ImageButton::GetAccessibleState(state);
   GetTooltipText(gfx::Point(), &state->name);
 }
 
 }  // namespace views