Mac build fix

base/debug_util_posix.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 "build/build_config.h"
 #include "base/debug_util.h"
 
 #if defined(OS_LINUX)
 #include <unistd.h>
 #include <execinfo.h>
@@ skipping 101 matching lines @@
 void StackTrace::PrintBacktrace() {
   fflush(stderr);
   backtrace_symbols_fd(&trace_[0], trace_.size(), STDERR_FILENO);
 }
 
 #elif defined(OS_MACOSX)
 
 // TODO(port): complete this code
 StackTrace::StackTrace() { }
 
-StackTrace::PrintBacktrace() {
+void StackTrace::PrintBacktrace() {
   NOTIMPLEMENTED();
 }
 
 #endif  // defined(OS_MACOSX)
 
 const void *const *StackTrace::Addresses(size_t* count) {
   *count = trace_.size();
   if (trace_.size())
     return &trace_[0];
   return NULL;
 }