Use SequencedWorkerPool for disk operations in TraceSubscriberStdio.

chrome/browser/ui/webui/tracing_ui.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 "chrome/browser/ui/webui/tracing_ui.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 55 matching lines @@
 
   // WebUIMessageHandler implementation.
   virtual void RegisterMessages();
 
   // SelectFileDialog::Listener implementation
   virtual void FileSelected(const FilePath& path, int index, void* params);
   virtual void FileSelectionCanceled(void* params);
 
   // TraceSubscriber implementation.
   virtual void OnEndTracingComplete();
-  virtual void OnTraceDataCollected(const std::string& trace_fragment);
+  virtual void OnTraceDataCollected(
+      const scoped_refptr<base::RefCountedString>& trace_fragment);
   virtual void OnTraceBufferPercentFullReply(float percent_full);
 
   // GpuDataManagerObserver implementation.
   virtual void OnGpuInfoUpdate() OVERRIDE;
 
   // Messages.
   void OnTracingControllerInitialized(const ListValue* list);
   void OnBeginTracing(const ListValue* list);
   void OnEndTracingAsync(const ListValue* list);
   void OnBeginRequestBufferPercentFull(const ListValue* list);
@@ skipping 285 matching lines @@
   }
 }
 
 void TracingMessageHandler::OnEndTracingComplete() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   trace_enabled_ = false;
   web_ui()->CallJavascriptFunction("tracingController.onEndTracingComplete");
 }
 
 void TracingMessageHandler::OnTraceDataCollected(
-    const std::string& trace_fragment) {
+    const scoped_refptr<base::RefCountedString>& trace_fragment) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   base::debug::TraceResultBuffer::SimpleOutput output;
   base::debug::TraceResultBuffer trace_buffer;
   trace_buffer.SetOutputCallback(output.GetCallback());
   output.Append("tracingController.onTraceDataCollected(");
   trace_buffer.Start();
-  trace_buffer.AddFragment(trace_fragment);
+  trace_buffer.AddFragment(trace_fragment->data());
   trace_buffer.Finish();
   output.Append(");");
 
   web_ui()->GetWebContents()->GetRenderViewHost()->
       ExecuteJavascriptInWebFrame(string16(), UTF8ToUTF16(output.json_output));
 }
 
 void TracingMessageHandler::OnTraceBufferPercentFullReply(float percent_full) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   web_ui()->CallJavascriptFunction(
@@ skipping 10 matching lines @@
 //
 ////////////////////////////////////////////////////////////////////////////////
 
 TracingUI::TracingUI(content::WebUI* web_ui) : WebUIController(web_ui) {
   web_ui->AddMessageHandler(new TracingMessageHandler());
 
   // Set up the chrome://tracing/ source.
   Profile::FromWebUI(web_ui)->
       GetChromeURLDataManager()->AddDataSource(CreateTracingHTMLSource());
 }