Style fix for member variable.

content/browser/trace_subscriber_stdio.h

 // 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.
 
 #ifndef CONTENT_BROWSER_TRACE_SUBSCRIBER_STDIO_H_
 #define CONTENT_BROWSER_TRACE_SUBSCRIBER_STDIO_H_
 #pragma once
 
 #include <string>
 
 #include "base/file_util.h"
 #include "content/browser/trace_controller.h"
 
 // Stdio implementation of TraceSubscriber. Use this to write traces to a file.
 class TraceSubscriberStdio : public TraceSubscriber {
  public:
   // Creates or overwrites the specified file. Check IsValid() for success.
   explicit TraceSubscriberStdio(const FilePath& path);
 
   // Returns TRUE if we're currently writing data to a file.
   bool IsValid();
 
   // Implementation of TraceSubscriber
   virtual void OnEndTracingComplete();
   virtual void OnTraceDataCollected(const std::string& json_events);
 
   virtual ~TraceSubscriberStdio();
 
  private:
-  FILE* m_file;
+  FILE* file_;
 };
 
 #endif  // CONTENT_BROWSER_TRACE_SUBSCRIBER_STDIO_H_