Add support for user defined "pool" to GN.

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 204 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 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[];
 extern const char kPrint_Help[];
 Value RunPrint(Scope* scope,
                const FunctionCallNode* function,
                const std::vector<Value>& args,
                Err* err);
 
 extern const char kProcessFileTemplate[];
 extern const char kProcessFileTemplate_HelpShort[];
@@ skipping 244 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_