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

ui/views/controls/styled_label.h

Index: ui/views/controls/styled_label.h
diff --git a/ui/views/controls/styled_label.h b/ui/views/controls/styled_label.h
index d74def2308605d3fb4bacb1fb9d3582761ff1d3c..4c599a0d438c5de58e98cd5cde3927a8ccdb7e86 100644
--- a/ui/views/controls/styled_label.h
+++ b/ui/views/controls/styled_label.h
@@ -87,7 +87,7 @@ class VIEWS_EXPORT StyledLabel : public View, public LinkListener {
 
   // View implementation:
   virtual gfx::Insets GetInsets() const OVERRIDE;
-  virtual int GetHeightForWidth(int w) OVERRIDE;
+  virtual int GetHeightForWidth(int w) const OVERRIDE;
   virtual void Layout() OVERRIDE;
   virtual void PreferredSizeChanged() OVERRIDE;
 
@@ -138,7 +138,7 @@ class VIEWS_EXPORT StyledLabel : public View, public LinkListener {
 
   // This variable saves the result of the last GetHeightForWidth call in order
   // to avoid repeated calculation.
-  gfx::Size calculated_size_;
+  mutable gfx::Size calculated_size_;
 
   // Background color on which the label is drawn, for auto color readability.
   SkColor displayed_on_background_color_;