Make HeapObjectHeader::checkHeader private.

third_party/WebKit/Source/platform/heap/Member.h

Index: third_party/WebKit/Source/platform/heap/Member.h
diff --git a/third_party/WebKit/Source/platform/heap/Member.h b/third_party/WebKit/Source/platform/heap/Member.h
index 0baa9a97a09926290569ea408615a9c562e5d618..53082fc8fccdde7900e61c6439cbd4849c5bd46a 100644
--- a/third_party/WebKit/Source/platform/heap/Member.h
+++ b/third_party/WebKit/Source/platform/heap/Member.h
@@ -155,8 +155,10 @@ class MemberBase {
     // but we cannot call it here because it requires to include T.h.
     // So we currently only try to implement the check for (a), but do
     // not insist that T's definition is in scope.
-    if (IsFullyDefined<T>::value && !IsGarbageCollectedMixin<T>::value)
-      HeapObjectHeader::fromPayload(m_raw)->checkHeader();
+    if (IsFullyDefined<T>::value && !IsGarbageCollectedMixin<T>::value) {
+      // |fromPayload| checks the integrity of the |HeapObjectHeader|.
+      (void)HeapObjectHeader::fromPayload(m_raw);
+    }
 #endif
 #endif
   }