Use FILE thread for disk operations in TraceSubscriberStdio

base/debug/trace_event_impl.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 BASE_DEBUG_TRACE_EVENT_IMPL_H_
 #define BASE_DEBUG_TRACE_EVENT_IMPL_H_
 #pragma once
 
 #include "build/build_config.h"
@@ skipping 24 matching lines @@
 #define TRACE_EVENT_INSTANT_ETW(name, id, extra) \
     base::debug::TraceLog::AddTraceEventEtw( \
         TRACE_EVENT_PHASE_INSTANT, \
         name, reinterpret_cast<const void*>(id), extra)
 
 template <typename Type>
 struct StaticMemorySingletonTraits;
 
 namespace base {
 
-class RefCountedString;
-
 namespace debug {
 
 const int kTraceMaxNumArgs = 2;
 
 // Output records are "Events" and can be obtained via the
 // OutputCallback whenever the tracing system decides to flush. This
 // can happen at any time, on any thread, or you can programatically
 // force it to happen.
 class BASE_EXPORT TraceEvent {
  public:
@@ skipping 138 matching lines @@
   void SetEnabled(bool enabled);
   bool IsEnabled() { return enabled_; }
 
   float GetBufferPercentFull() const;
 
   // When enough events are collected, they are handed (in bulk) to
   // the output callback. If no callback is set, the output will be
   // silently dropped. The callback must be thread safe. The string format is
   // undefined. Use TraceResultBuffer to convert one or more trace strings to
   // JSON.
-  typedef RefCountedData<std::string> RefCountedString;
-  typedef base::Callback<void(const scoped_refptr<RefCountedString>&)>
+  typedef base::Callback<void(const scoped_refptr<base::RefCountedString>&)>

[Iain Merrick, 2012/02/08 12:07:05]

Previously we were converting from RefCountedData -> string, now we just pass
RefCountedString with no conversion.

The only difference is that RefCountedData is a subclass of RefCounted, whereas
RefCountedString is RefCountedThreadSafe. Joth, do you think that will cause any
issues for the startup tracing?

[joth, 2012/02/08 13:22:20]

Should be fine. This sounds a good change.

       OutputCallback;
   void SetOutputCallback(const OutputCallback& cb);
 
   // The trace buffer does not flush dynamically, so when it fills up,
   // subsequent trace events will be dropped. This callback is generated when
   // the trace buffer is full. The callback must be thread safe.
   typedef base::Callback<void(void)> BufferFullCallback;
   void SetBufferFullCallback(const BufferFullCallback& cb);
 
   // Flushes all logged data to the callback.
@@ skipping 78 matching lines @@
 
   int process_id_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceLog);
 };
 
 }  // namespace debug
 }  // namespace base
 
 #endif  // BASE_DEBUG_TRACE_EVENT_IMPL_H_