Add a Content API around TracingController.

content/browser/trace_subscriber_stdio.h

 // 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.
 
 #ifndef CONTENT_BROWSER_TRACE_SUBSCRIBER_STDIO_H_
 #define CONTENT_BROWSER_TRACE_SUBSCRIBER_STDIO_H_
 #pragma once
 
 #include <string>
 
+#include "base/compiler_specific.h"
 #include "base/file_util.h"
-#include "content/browser/trace_controller.h"
+#include "content/public/browser/trace_subscriber.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
 class TraceSubscriberStdioImpl;
 
 // Stdio implementation of TraceSubscriber. Use this to write traces to a file.
-class CONTENT_EXPORT TraceSubscriberStdio : public TraceSubscriber {
+class CONTENT_EXPORT TraceSubscriberStdio
+    : NON_EXPORTED_BASE(public content::TraceSubscriber) {
  public:
   // Creates or overwrites the specified file. Check IsValid() for success.
   explicit TraceSubscriberStdio(const FilePath& path);
   virtual ~TraceSubscriberStdio();
 
   // Implementation of TraceSubscriber
   virtual void OnEndTracingComplete() OVERRIDE;
   virtual void OnTraceDataCollected(
       const scoped_refptr<base::RefCountedString>& data_ptr) OVERRIDE;
 
  private:
   scoped_refptr<TraceSubscriberStdioImpl> impl_;
   DISALLOW_COPY_AND_ASSIGN(TraceSubscriberStdio);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_TRACE_SUBSCRIBER_STDIO_H_