Hook up symbol files to the Windows GN build.

tools/gn/ninja_binary_target_writer.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/ninja_binary_target_writer.h"
 
 #include <set>
 
 #include "base/strings/string_util.h"
 #include "tools/gn/config_values_extractors.h"
@@ skipping 107 matching lines @@
     out_ << std::endl;
 
   WRITE_FLAGS(cflags)
   WRITE_FLAGS(cflags_c)
   WRITE_FLAGS(cflags_cc)
   WRITE_FLAGS(cflags_objc)
   WRITE_FLAGS(cflags_objcc)
 
 #undef WRITE_FLAGS
 
+  // Write some variables about the target for the toolchain definition to use.
+  out_ << "target_name = " << target_->label().name() << std::endl;
+  out_ << "target_out_dir = ";
+  path_output_.WriteDir(out_, helper_.GetTargetOutputDir(target_),
+                        PathOutput::DIR_NO_LAST_SLASH);
   out_ << std::endl;
+  out_ << "root_out_dir = ";
+  path_output_.WriteDir(out_, target_->settings()->toolchain_output_subdir(),
+                        PathOutput::DIR_NO_LAST_SLASH);
+  out_ << std::endl << std::endl;
 }
 
 void NinjaBinaryTargetWriter::WriteSources(
     std::vector<OutputFile>* object_files) {
   const Target::FileList& sources = target_->sources();
   object_files->reserve(sources.size());
 
   std::string implicit_deps =
       WriteInputDepsStampAndGetDep(std::vector<const Target*>());
 
@@ skipping 319 matching lines @@
     }
 
     // Data files.
     const std::vector<SourceFile>& data = target_->data();
     for (size_t i = 0; i < data.size(); i++) {
       out_ << " ";
       path_output_.WriteFile(out_, data[i]);
     }
   }
 }