Remove use of <iostream> where unnecessary.

base/debug/stack_trace_win.cc

 // Copyright (c) 2011 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/debug/stack_trace.h"
 
 #include <windows.h>
 #include <dbghelp.h>
 
-#include <iostream>
+#include <ostream>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 #include "base/synchronization/lock.h"
 
 namespace base {
 namespace debug {
 
 namespace {
@@ skipping 180 matching lines @@
       (*os) << "\t" << trace_[i] << "\n";
     }
   } else {
     (*os) << "Backtrace:\n";
     context->OutputTraceToStream(trace_, count_, os);
   }
 }
 
 }  // namespace debug
 }  // namespace base