Add not_needed function

tools/gn/functions.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_FUNCTIONS_H_
 #define TOOLS_GN_FUNCTIONS_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 203 matching lines @@
 
 extern const char kLoadableModule[];
 extern const char kLoadableModule_HelpShort[];
 extern const char kLoadableModule_Help[];
 Value RunLoadableModule(Scope* scope,
                         const FunctionCallNode* function,
                         const std::vector<Value>& args,
                         BlockNode* block,
                         Err* err);
 
+extern const char kNotNeeded[];
+extern const char kNotNeeded_HelpShort[];
+extern const char kNotNeeded_Help[];
+Value RunNotNeeded(Scope* scope,
+                   const FunctionCallNode* function,
+                   const ListNode* args_list,
+                   Err* err);
+
 extern const char kPool[];
 extern const char kPool_HelpShort[];
 extern const char kPool_Help[];
 Value RunPool(const FunctionCallNode* function,
               const std::vector<Value>& args,
               Scope* block_scope,
               Err* err);
 
 extern const char kPrint[];
 extern const char kPrint_HelpShort[];
@@ skipping 261 matching lines @@
   Scope* scope_;
   const FunctionCallNode* function_;
   const char* type_description_;
 
   // Set to true when the key is added to the scope so we don't try to
   // delete nonexistant keys which will cause assertions.
   bool key_added_;
 };
 
 #endif  // TOOLS_GN_FUNCTIONS_H_