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

ui/views/test/child_modal_window.cc

Index: ui/views/test/child_modal_window.cc
diff --git a/ui/views/test/child_modal_window.cc b/ui/views/test/child_modal_window.cc
index 2292fd61f7aed1d534174ec9e6764bf9c3d73568..fc19ddfd31fab1f4cd1d79bd43a14897d66c05f7 100644
--- a/ui/views/test/child_modal_window.cc
+++ b/ui/views/test/child_modal_window.cc
@@ -61,7 +61,7 @@ class ChildModalWindow : public WidgetDelegateView {
  private:
   // Overridden from View:
   virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
-  virtual gfx::Size GetPreferredSize() OVERRIDE;
+  virtual gfx::Size GetPreferredSize() const OVERRIDE;
 
   // Overridden from WidgetDelegate:
   virtual View* GetContentsView() OVERRIDE;
@@ -87,7 +87,7 @@ void ChildModalWindow::OnPaint(gfx::Canvas* canvas) {
   canvas->FillRect(GetLocalBounds(), kChildColor);
 }
 
-gfx::Size ChildModalWindow::GetPreferredSize() {
+gfx::Size ChildModalWindow::GetPreferredSize() const {
   return gfx::Size(kChildWindowWidth, kChildWindowHeight);
 }