Add a "gn path" command for finding deps.

tools/gn/commands.cc

 // 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.
 
 #include "tools/gn/commands.h"
 
 #include "base/command_line.h"
 #include "tools/gn/builder.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/item.h"
@@ skipping 344 matching lines @@
                                        &Run##cmd);
 
     INSERT_COMMAND(Args)
     INSERT_COMMAND(Check)
     INSERT_COMMAND(Clean)
     INSERT_COMMAND(Desc)
     INSERT_COMMAND(Gen)
     INSERT_COMMAND(Format)
     INSERT_COMMAND(Help)
     INSERT_COMMAND(Ls)
+    INSERT_COMMAND(Path)
     INSERT_COMMAND(Refs)
 
     #undef INSERT_COMMAND
   }
   return info_map;
 }
 
 const Target* ResolveTargetFromCommandLineString(
     Setup* setup,
     const std::string& label_string) {
@@ skipping 105 matching lines @@
   }
 }
 
 void FilterAndPrintTargetSet(bool indent,
                              const std::set<const Target*>& targets) {
   std::vector<const Target*> target_vector(targets.begin(), targets.end());
   FilterAndPrintTargets(indent, &target_vector);
 }
 
 }  // namespace commands