Update from https://crrev.com/317530

tools/clang/blink_gc_plugin/tests/traceimpl.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "traceimpl.h"
 
 namespace blink {
 
 void TraceImplExtern::trace(Visitor* visitor) {
   traceImpl(visitor);
 }
 
 template <typename VisitorDispatcher>
 inline void TraceImplExtern::traceImpl(VisitorDispatcher visitor) {
-  visitor->trace(m_x);
+  visitor->trace(x_);
 }
+
+void TraceImplBaseExtern::trace(Visitor* visitor) {
+  traceImpl(visitor);
 }
+
+template <typename VisitorDispatcher>
+inline void TraceImplBaseExtern::traceImpl(VisitorDispatcher visitor) {
+  visitor->trace(x_);
+  Base::trace(visitor);
+}
+
+}