Re-land r406064 "[GN] Add JSON project writer".

tools/gn/commands.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_COMMANDS_H_
 #define TOOLS_GN_COMMANDS_H_
 
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/strings/string_piece.h"
+#include "base/values.h"
 #include "tools/gn/target.h"
 #include "tools/gn/unique_vector.h"
 
 class BuildSettings;
 class Config;
 class LabelPattern;
 class Setup;
 class SourceFile;
 class Target;
 class Toolchain;
@@ skipping 148 matching lines @@
     "      accordingly. When unspecified, the target's testonly flags are\n"\
     "      ignored.\n"
 
 // Applies any testonly and type filters specified on the command line,
 // and prints the targets as specified by the --as command line flag.
 //
 // If indent is true, the results will be indented two spaces.
 //
 // The vector will be modified so that only the printed targets will remain.
 void FilterAndPrintTargets(bool indent, std::vector<const Target*>* targets);
+void FilterAndPrintTargets(std::vector<const Target*>* targets,
+                           base::ListValue* out);
+
 void FilterAndPrintTargetSet(bool indent,
                              const std::set<const Target*>& targets);
+void FilterAndPrintTargetSet(const std::set<const Target*>& targets,
+                             base::ListValue* out);
 
 // Extra help from command_check.cc
 extern const char kNoGnCheck_Help[];
 
 }  // namespace commands
 
 #endif  // TOOLS_GN_COMMANDS_H_