Add not_needed function

tools/gn/scope.h

 // Copyright (c) 2013 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_GN_SCOPE_H_
 #define TOOLS_GN_SCOPE_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 188 matching lines @@
   // Templates associated with this scope. A template can only be set once, so
   // AddTemplate will fail and return false if a rule with that name already
   // exists. GetTemplate returns NULL if the rule doesn't exist, and it will
   // check all containing scoped rescursively.
   bool AddTemplate(const std::string& name, const Template* templ);
   const Template* GetTemplate(const std::string& name) const;
 
   // Marks the given identifier as (un)used in the current scope.
   void MarkUsed(const base::StringPiece& ident);
   void MarkAllUsed();
+  void MarkAllUsed(const std::set<std::string>& excluded_values);
   void MarkUnused(const base::StringPiece& ident);
 
   // Checks to see if the scope has a var set that hasn't been used. This is
   // called before replacing the var with a different one. It does not check
   // containing scopes.
   //
   // If the identifier is present but hasnn't been used, return true.
   bool IsSetButUnused(const base::StringPiece& ident) const;
 
   // Checks the scope to see if any values were set but not used, and fills in
@@ skipping 156 matching lines @@
 
   typedef std::set<ProgrammaticProvider*> ProviderSet;
   ProviderSet programmatic_providers_;
 
   SourceDir source_dir_;
 
   DISALLOW_COPY_AND_ASSIGN(Scope);
 };
 
 #endif  // TOOLS_GN_SCOPE_H_