Factor out the layout code from OpaqueBrowserFrameView for testing.

ui/views/controls/button/image_button.h

Index: ui/views/controls/button/image_button.h
diff --git a/ui/views/controls/button/image_button.h b/ui/views/controls/button/image_button.h
index 4015def5a6a1e71d8f12ccc500baf33a74926b91..5ea0fa91ead76d66d1fd82d0a08eb53197a54fb7 100644
--- a/ui/views/controls/button/image_button.h
+++ b/ui/views/controls/button/image_button.h
@@ -20,6 +20,8 @@ namespace views {
 
 class VIEWS_EXPORT ImageButton : public CustomButton {
  public:
+  static const char kViewClassName[];
+
   enum HorizontalAlignment {
     ALIGN_LEFT = 0,
     ALIGN_CENTER,
@@ -56,6 +58,7 @@ class VIEWS_EXPORT ImageButton : public CustomButton {
 
   // Overridden from View:
   virtual gfx::Size GetPreferredSize() OVERRIDE;
+  virtual const char* GetClassName() const OVERRIDE;
   virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
 
   // Sets preferred size, so it could be correctly positioned in layout even if