INPUT element: Fix a DCHECK failure in RadioInputType::findNextFocusableRadioButtonInGroup.

third_party/WebKit/Source/core/html/HTMLInputElement.h

Index: third_party/WebKit/Source/core/html/HTMLInputElement.h
diff --git a/third_party/WebKit/Source/core/html/HTMLInputElement.h b/third_party/WebKit/Source/core/html/HTMLInputElement.h
index 77045bb05d11b7726b483830780e0900000d7777..c181b0ef5243761ac4f8f22ed95e4422584ab156 100644
--- a/third_party/WebKit/Source/core/html/HTMLInputElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLInputElement.h
@@ -25,6 +25,7 @@
 #ifndef HTMLInputElement_h
 #define HTMLInputElement_h
 
+#include "base/gtest_prod_util.h"
 #include "core/CoreExport.h"
 #include "core/html/TextControlElement.h"
 #include "core/html/forms/StepRange.h"
@@ -429,6 +430,8 @@ class CORE_EXPORT HTMLInputElement : public TextControlElement {
   // element lives on.
   Member<HTMLImageLoader> m_imageLoader;
   Member<ListAttributeTargetObserver> m_listAttributeTargetObserver;
+
+  FRIEND_TEST_ALL_PREFIXES(HTMLInputElementTest, RadioKeyDownDCHECKFailure);
 };
 
 }  // namespace blink