Use SequencedWorkerPool for disk operations in TraceSubscriberStdio.

content/browser/trace_message_filter.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 "content/browser/trace_message_filter.h"
 
 #include "content/browser/trace_controller.h"
 #include "content/common/child_process_messages.h"
 
 using content::BrowserMessageFilter;
@@ skipping 78 matching lines @@
     const std::vector<std::string>& known_categories) {
   // is_awaiting_end_ack_ should always be true here, but check in case the
   // child process is compromised.
   if (is_awaiting_end_ack_) {
     is_awaiting_end_ack_ = false;
     TraceController::GetInstance()->OnEndTracingAck(known_categories);
   }
 }
 
 void TraceMessageFilter::OnTraceDataCollected(const std::string& data) {
-  TraceController::GetInstance()->OnTraceDataCollected(
-      make_scoped_refptr(new base::debug::TraceLog::RefCountedString(data)));
+  scoped_refptr<base::RefCountedString> data_ptr(new base::RefCountedString());
+  data_ptr->data() = data;
+  TraceController::GetInstance()->OnTraceDataCollected(data_ptr);
 }
 
 void TraceMessageFilter::OnTraceBufferFull() {
   TraceController::GetInstance()->OnTraceBufferFull();
 }
 
 void TraceMessageFilter::OnTraceBufferPercentFullReply(float percent_full) {
   if (is_awaiting_bpf_ack_) {
     is_awaiting_bpf_ack_ = false;
     TraceController::GetInstance()->OnTraceBufferPercentFullReply(
         percent_full);
   }
 }