Add utf_string_conversions to base namespace.

chrome/browser/extensions/api/file_system/file_system_api_unittest.cc

 // Copyright (c) 2012 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 "base/file_util.h"
 #include "base/files/file_path.h"
 #include "base/string_split.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/extensions/api/file_system/file_system_api.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 30 matching lines @@
 
   if (!extensions.empty()) {
     option->extensions.reset(new std::vector<std::string>());
     base::SplitString(extensions, ',', option->extensions.get());
   }
 
   return option;
 }
 
 #if defined(OS_WIN)
-#define ToStringType UTF8ToWide
+#define ToStringType base::UTF8ToWide
 #else
 #define ToStringType
 #endif
 
 }  // namespace
 
 class FileSystemApiUnitTest : public testing::Test {
 };
 
 TEST_F(FileSystemApiUnitTest, FileSystemChooseEntryFunctionFileTypeInfoTest) {
@@ skipping 116 matching lines @@
   // TODO(thorogood): Fix this test on Windows.
   // Filter out absolute paths with no basename.
   opt_name = std::string("/");
   FileSystemChooseEntryFunction::BuildSuggestion(&opt_name, &suggested_name,
       &suggested_extension);
   EXPECT_FALSE(suggested_name.IsAbsolute());
   EXPECT_TRUE(suggested_name.MaybeAsASCII().empty());
   EXPECT_TRUE(suggested_extension.empty());
 #endif
 }