Add ninja dependency reference to gen written files.

tools/gn/function_write_file.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 <iostream>
 #include <sstream>
 
 #include "base/files/file_util.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
@@ skipping 96 matching lines @@
   const SourceDir& cur_dir = scope->GetSourceDir();
   SourceFile source_file = cur_dir.ResolveRelativeFile(args[0], err,
       scope->settings()->build_settings()->root_path_utf8());
   if (err->has_error())
     return Value();
   if (!EnsureStringIsInOutputDir(
           scope->settings()->build_settings()->build_dir(),
           source_file.value(), args[0].origin(), err))
     return Value();
   g_scheduler->AddWrittenFile(source_file);  // Track that we wrote this file.
+  // Track how to recreate this file, since we write it a gen time.

[brettw, 2015/07/06 21:29:39]

Can you put a blank line above this?

[Peter Mayo, 2015/07/06 22:09:00]

Done.

+  // Note this is a hack since the correct output is not a dependency proper,
+  // but an addition of this file to the output of the gn rule that writes it.

[brettw, 2015/07/06 21:29:39]

can you append something like "so if this file is missing the build will be
re-run."

[Peter Mayo, 2015/07/06 22:09:00]

Done.

+  g_scheduler->AddGenDependency(
+      scope->settings()->build_settings()->GetFullPath(source_file));
 
   // Compute output.
   std::ostringstream contents;
   if (args[1].type() == Value::LIST) {
     const std::vector<Value>& list = args[1].list_value();
     for (const auto& cur : list)
       contents << cur.ToString(false) << std::endl;
   } else {
     contents << args[1].ToString(false);
   }
@@ skipping 18 matching lines @@
   if (DoWriteFile(file_path, new_contents.c_str(), int_size)
       != int_size) {
     *err = Err(function->function(), "Unable to write file.",
                "I was writing \"" + FilePathToUTF8(file_path) + "\".");
     return Value();
   }
   return Value();
 }
 
 }  // namespace functions