Use a direct include of strings headers in base/.

base/environment.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/environment.h"
 
 #if defined(OS_POSIX)
 #include <stdlib.h>
 #elif defined(OS_WIN)
 #include <windows.h>
 #endif
 
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 
 #if defined(OS_WIN)
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/utf_string_conversions.h"
 #endif
 
 namespace {
 
 class EnvironmentImpl : public base::Environment {
  public:
@@ skipping 94 matching lines @@
 // static
 Environment* Environment::Create() {
   return new EnvironmentImpl();
 }
 
 bool Environment::HasVar(const char* variable_name) {
   return GetVar(variable_name, NULL);
 }
 
 }  // namespace base