Remove <iostream> where possible.

base/linked_ptr_unittest.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 <string>
-#include <iostream>
 
 #include "base/linked_ptr.h"
 
 #include "base/string_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 
 int num = 0;
 
@@ skipping 84 matching lines @@
     "A2 dtor\n"
     "A0 use\n"
     "A0 use\n"
     "A1 use\n"
     "A3 ctor\n"
     "A0 dtor\n"
     "A3 dtor\n"
     "A1 dtor\n"
   );
 }