Use FILE thread for disk operations in TraceSubscriberStdio

base/debug/trace_event_impl.h

Index: base/debug/trace_event_impl.h
===================================================================
--- base/debug/trace_event_impl.h	(revision 120962)
+++ base/debug/trace_event_impl.h	(working copy)
@@ -42,8 +42,6 @@
 
 namespace base {
 
-class RefCountedString;
-
 namespace debug {
 
 const int kTraceMaxNumArgs = 2;
@@ -202,8 +200,7 @@
   // 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);