Begin the first small step towards using FilePath everywhere:

base/icu_util.cc

 // Copyright (c) 2006-2008 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 "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #include <string>
 
 #include "base/icu_util.h"
 
+#include "base/file_path.h"
+#include "base/file_util.h"
 #include "base/logging.h"
-#include "base/file_util.h"
 #include "base/path_service.h"
 #include "base/sys_string_conversions.h"
 #include "unicode/putil.h"
 #include "unicode/udata.h"
 
 #define ICU_UTIL_DATA_FILE      0
 #define ICU_UTIL_DATA_SHARED    1
 #define ICU_UTIL_DATA_STATIC    2
 
 #ifndef ICU_UTIL_DATA_IMPL
@@ skipping 42 matching lines @@
   UErrorCode err = U_ZERO_ERROR;
   udata_setCommonData(reinterpret_cast<void*>(addr), &err);
   return err == U_ZERO_ERROR;
 #elif (ICU_UTIL_DATA_IMPL == ICU_UTIL_DATA_STATIC)
   // Mac bundles the ICU data in.
   return true;
 #elif (ICU_UTIL_DATA_IMPL == ICU_UTIL_DATA_FILE)
   // For now, expect the data file to be alongside the executable.
   // This is sufficient while we work on unit tests, but will eventually
   // likely live in a data directory.
-  std::wstring data_path;
+  FilePath data_path;
   bool path_ok = PathService::Get(base::DIR_EXE, &data_path);
   DCHECK(path_ok);
-  u_setDataDirectory(base::SysWideToNativeMB(data_path).c_str());
+  u_setDataDirectory(
+      base::SysWideToNativeMB(data_path.ToWStringHack()).c_str());
   // Only look for the packaged data file;
   // the default behavior is to look for individual files.
   UErrorCode err = U_ZERO_ERROR;
   udata_setFileAccess(UDATA_ONLY_PACKAGES, &err);
   return err == U_ZERO_ERROR;
 #endif
 }
 
 }  // namespace icu_util