Add GN function get_label_info

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 129 matching lines @@
                     Err* err);
 
 extern const char kGetEnv[];
 extern const char kGetEnv_HelpShort[];
 extern const char kGetEnv_Help[];
 Value RunGetEnv(Scope* scope,
                 const FunctionCallNode* function,
                 const std::vector<Value>& args,
                 Err* err);
 
+extern const char kGetLabelInfo[];
+extern const char kGetLabelInfo_HelpShort[];
+extern const char kGetLabelInfo_Help[];
+Value RunGetLabelInfo(Scope* scope,
+                      const FunctionCallNode* function,
+                      const std::vector<Value>& args,
+                      Err* err);
+
 extern const char kGetTargetOutputs[];
 extern const char kGetTargetOutputs_HelpShort[];
 extern const char kGetTargetOutputs_Help[];
 Value RunGetTargetOutputs(Scope* scope,
                           const FunctionCallNode* function,
                           const std::vector<Value>& args,
                           Err* err);
 
 extern const char kGroup[];
 extern const char kGroup_HelpShort[];
@@ skipping 241 matching lines @@
 // Returns the name of the toolchain for the given scope.
 const Label& ToolchainLabelForScope(const Scope* scope);
 
 // Generates a label for the given scope, using the current directory and
 // toolchain, and the given name.
 Label MakeLabelForScope(const Scope* scope,
                         const FunctionCallNode* function,
                         const std::string& name);
 
 #endif  // TOOLS_GN_FUNCTIONS_H_