GN: Move towards only using / on Windows

tools/gn/setup.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/setup.h"
 
 #include <stdlib.h>
 
 #include <algorithm>
 
@@ skipping 276 matching lines @@
   }
 
   if (scheduler_.verbose_logging())
     scheduler_.Log("Using source root", FilePathToUTF8(root_path));
   build_settings_.SetRootPath(root_path);
 
   return true;
 }
 
 bool Setup::FillBuildDir(const std::string& build_dir) {
-  std::string normalized_build_dir = PathToSystem(build_dir);
-
   SourceDir resolved =
       SourceDirForCurrentDirectory(build_settings_.root_path()).
-          ResolveRelativeDir(normalized_build_dir);
+          ResolveRelativeDir(build_dir);
   if (resolved.is_null()) {
     Err(Location(), "Couldn't resolve build directory.",
         "The build directory supplied (\"" + build_dir + "\") was not valid.").
         PrintToStdout();
     return false;
   }
 
   if (scheduler_.verbose_logging())
     scheduler_.Log("Using build dir", resolved.value());
   build_settings_.SetBuildDir(resolved);
   return true;
 }
 
 void Setup::FillPythonPath() {
 #if defined(OS_WIN)
   // Find Python on the path so we can use the absolute path in the build.
   const base::char16 kGetPython[] =
       L"cmd.exe /c python -c \"import sys; print sys.executable\"";
   std::string python_path;
   if (base::GetAppOutput(kGetPython, &python_path)) {
     base::TrimWhitespaceASCII(python_path, base::TRIM_ALL, &python_path);
     if (scheduler_.verbose_logging())
       scheduler_.Log("Found python", python_path);
   } else {
     scheduler_.Log("WARNING", "Could not find python on path, using "
         "just \"python.exe\"");
     python_path = "python.exe";
   }
-  build_settings_.set_python_path(
-      base::FilePath(base::UTF8ToUTF16(python_path)));
+  build_settings_.set_python_path(base::FilePath(base::UTF8ToUTF16(python_path))
+                                      .NormalizePathSeparatorsTo('/'));
 #else
   build_settings_.set_python_path(base::FilePath("python"));
 #endif
 }
 
 bool Setup::RunConfigFile() {
   if (scheduler_.verbose_logging())
     scheduler_.Log("Got dotfile", FilePathToUTF8(dotfile_name_));
 
   dotfile_input_file_.reset(new InputFile(SourceFile("//.gn")));
@@ skipping 91 matching lines @@
 }
 
 void DependentSetup::RunPreMessageLoop() {
   CommonSetup::RunPreMessageLoop();
 }
 
 bool DependentSetup::RunPostMessageLoop() {
   return CommonSetup::RunPostMessageLoop();
 }