Use Shadow DOM to display fallback content for images

Source/core/html/forms/BaseButtonInputType.h

Index: Source/core/html/forms/BaseButtonInputType.h
diff --git a/Source/core/html/forms/BaseButtonInputType.h b/Source/core/html/forms/BaseButtonInputType.h
index 84e268f23f420e1175813bb277e31bb97ed4f0ce..c44b51eb44b9cfbadb083c3d6ea75372c0b097a3 100644
--- a/Source/core/html/forms/BaseButtonInputType.h
+++ b/Source/core/html/forms/BaseButtonInputType.h
@@ -41,13 +41,14 @@ protected:
     BaseButtonInputType(HTMLInputElement& element) : BaseClickableWithKeyInputType(element) { }
 
 private:
-    virtual void createShadowSubtree() OVERRIDE;
-    virtual void valueAttributeChanged() OVERRIDE;
     virtual bool shouldSaveAndRestoreFormControlState() const OVERRIDE;
     virtual bool appendFormData(FormDataList&, bool) const OVERRIDE;
     virtual RenderObject* createRenderer(RenderStyle*) const OVERRIDE;
     virtual bool storesValueSeparateFromAttribute() OVERRIDE;
     virtual void setValue(const String&, bool, TextFieldEventBehavior) OVERRIDE;
+protected:
+    virtual void createShadowSubtree() OVERRIDE;
+    virtual void valueAttributeChanged() OVERRIDE;
 };
 
 } // namespace blink