run iwyu on base!

base/string16.cc

 // Copyright (c) 2009 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 <stdio.h>
+#include <string.h>
+#include <string>
+
 #include "base/string16.h"
+#include "build/build_config.h"
 
 #if defined(WCHAR_T_IS_UTF16)
 
 #error This file should not be used on 2-byte wchar_t systems
 // If this winds up being needed on 2-byte wchar_t systems, either the
 // definitions below can be used, or the host system's wide character
 // functions like wmemcmp can be wrapped.
 
 #elif defined(WCHAR_T_IS_UTF32)
 
@@ skipping 55 matching lines @@
 
 template class std::basic_string<char16, base::string16_char_traits>;
 
 namespace base {
 std::ostream& operator<<(std::ostream& out, const string16& str) {
   return out << UTF16ToUTF8(str);
 }
 }
 
 #endif  // WCHAR_T_IS_UTF32