Update from https://crrev.com/308996

tools/clang/blink_gc_plugin/Config.h

 // 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.
 
 // This file defines the names used by GC infrastructure.
 
 // TODO: Restructure the name determination to use fully qualified names (ala,
 // blink::Foo) so that the plugin can be enabled for all of chromium. Doing so
 // would allow us to catch errors with structures outside of blink that might
 // have unsafe pointers to GC allocated blink structures.
@@ skipping 141 matching lines @@
 
   static bool IsIgnoreAnnotated(clang::Decl* decl) {
     return IsAnnotated(decl, "blink_gc_plugin_ignore");
   }
 
   static bool IsIgnoreCycleAnnotated(clang::Decl* decl) {
     return IsAnnotated(decl, "blink_gc_plugin_ignore_cycle") ||
            IsIgnoreAnnotated(decl);
   }
 
-  static bool IsVisitor(const std::string& name) { return name == "Visitor"; }
+  static bool IsVisitor(const std::string& name) {
+    return name == "Visitor" || name == "VisitorHelper";
+  }
 
   static bool IsTraceMethod(clang::FunctionDecl* method,
                             bool* isTraceAfterDispatch = 0) {
     if (method->getNumParams() != 1)
       return false;
 
     const std::string& name = method->getNameAsString();
     if (name != kTraceName && name != kTraceAfterDispatchName)
       return false;
 
@@ skipping 21 matching lines @@
   }
 
   static bool EndsWith(const std::string& str, const std::string& suffix) {
     if (suffix.size() > str.size())
       return false;
     return str.compare(str.size() - suffix.size(), suffix.size(), suffix) == 0;
   }
 };
 
 #endif  // TOOLS_BLINK_GC_PLUGIN_CONFIG_H_