blink_gc_plugin: retire overloaded traceImpl detection and handling.

tools/clang/blink_gc_plugin/CheckTraceVisitor.h

 // Copyright 2015 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.
 
 #ifndef TOOLS_BLINK_GC_PLUGIN_CHECK_TRACE_VISITOR_H_
 #define TOOLS_BLINK_GC_PLUGIN_CHECK_TRACE_VISITOR_H_
 
 #include <string>
 
 #include "RecordInfo.h"
 #include "clang/AST/AST.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 
 class RecordCache;
 class RecordInfo;
 
 // This visitor checks a tracing method by traversing its body.
 // - A member field is considered traced if it is referenced in the body.
 // - A base is traced if a base-qualified call to a trace method is found.
 class CheckTraceVisitor : public clang::RecursiveASTVisitor<CheckTraceVisitor> {
  public:
   CheckTraceVisitor(clang::CXXMethodDecl* trace,
                     RecordInfo* info,
                     RecordCache* cache);
 
-  bool delegates_to_traceimpl() const;
-
   bool VisitMemberExpr(clang::MemberExpr* member);
   bool VisitCallExpr(clang::CallExpr* call);
 
  private:
   bool IsTraceCallName(const std::string& name);
 
   clang::CXXRecordDecl* GetDependentTemplatedDecl(
       clang::CXXDependentScopeMemberExpr* expr);
 
   void CheckCXXDependentScopeMemberExpr(
       clang::CallExpr* call,
       clang::CXXDependentScopeMemberExpr* expr);
   bool CheckTraceBaseCall(clang::CallExpr* call);
   bool CheckTraceFieldMemberCall(clang::CXXMemberCallExpr* call);
   bool CheckTraceFieldCall(const std::string& name,
                            clang::CXXRecordDecl* callee,
                            clang::Expr* arg);
   bool CheckRegisterWeakMembers(clang::CXXMemberCallExpr* call);
 
   bool IsWeakCallback() const;
 
   void MarkTraced(RecordInfo::Fields::iterator it);
   void FoundField(clang::FieldDecl* field);
   void MarkAllWeakMembersTraced();
 
   clang::CXXMethodDecl* trace_;
   RecordInfo* info_;
   RecordCache* cache_;
-  bool delegates_to_traceimpl_;
 };
 
 #endif  // TOOLS_BLINK_GC_PLUGIN_CHECK_TRACE_VISITOR_H_