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

ui/views/controls/combobox/combobox.h

Index: ui/views/controls/combobox/combobox.h
diff --git a/ui/views/controls/combobox/combobox.h b/ui/views/controls/combobox/combobox.h
index 9b527d87b9f0fa0f63b5527117626d8e84f1dd2b..2c96176cfc6778bc1f98045ffa9ede093fd02cd9 100644
--- a/ui/views/controls/combobox/combobox.h
+++ b/ui/views/controls/combobox/combobox.h
@@ -93,7 +93,7 @@ class VIEWS_EXPORT Combobox : public MenuDelegate,
   bool invalid() const { return invalid_; }
 
   // Overridden from View:
-  virtual gfx::Size GetPreferredSize() OVERRIDE;
+  virtual gfx::Size GetPreferredSize() const OVERRIDE;
   virtual const char* GetClassName() const OVERRIDE;
   virtual bool SkipDefaultKeyEventProcessing(const ui::KeyEvent& e) OVERRIDE;
   virtual bool OnKeyPressed(const ui::KeyEvent& e) OVERRIDE;
@@ -109,7 +109,8 @@ class VIEWS_EXPORT Combobox : public MenuDelegate,
   virtual bool IsItemChecked(int id) const OVERRIDE;
   virtual bool IsCommandEnabled(int id) const OVERRIDE;
   virtual void ExecuteCommand(int id) OVERRIDE;
-  virtual bool GetAccelerator(int id, ui::Accelerator* accelerator) OVERRIDE;
+  virtual bool GetAccelerator(int id,
+                              ui::Accelerator* accelerator) const OVERRIDE;
 
   // Overridden from PrefixDelegate:
   virtual int GetRowCount() OVERRIDE;
@@ -200,7 +201,7 @@ class VIEWS_EXPORT Combobox : public MenuDelegate,
   base::Time closed_time_;
 
   // The maximum dimensions of the content in the dropdown
-  gfx::Size content_size_;
+  mutable gfx::Size content_size_;
 
   // The painters or images that are used when |style_| is STYLE_BUTTONS. The
   // first index means the state of unfocused or focused.