Add support for writing system traces at startup

content/browser/tracing/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_TRACING_TRACE_SUBSCRIBER_STDIO_H_
 #define CONTENT_BROWSER_TRACING_TRACE_SUBSCRIBER_STDIO_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "content/public/browser/trace_subscriber.h"
 #include "content/common/content_export.h"
 
 namespace base {
 class FilePath;
 }
 
 namespace content {
 
-class TraceSubscriberStdioImpl;
-
 // Stdio implementation of TraceSubscriber. Use this to write traces to a file.
 class CONTENT_EXPORT TraceSubscriberStdio
     : NON_EXPORTED_BASE(public TraceSubscriber) {
  public:
-  // Creates or overwrites the specified file. Check IsValid() for success.
-  explicit TraceSubscriberStdio(const base::FilePath& path);
+  enum FileType {

[sky, 2013/08/20 14:28:44]

Please add a description of what these mean.

[DaveMoore, 2013/08/20 14:58:00]

Done.

+    FILE_TYPE_ARRAY,
+    FILE_TYPE_PROPERTY_LIST
+  };
+
+  TraceSubscriberStdio(const base::FilePath& path,
+                       FileType file_type,
+                       bool has_system_trace);

[sky, 2013/08/20 14:28:44]

Add a description for has_system_trace.

[DaveMoore, 2013/08/20 14:58:00]

Done.

   virtual ~TraceSubscriberStdio();
 
   // Implementation of TraceSubscriber
   virtual void OnEndTracingComplete() OVERRIDE;
   virtual void OnTraceDataCollected(
       const scoped_refptr<base::RefCountedString>& data_ptr) OVERRIDE;
 
+  virtual void OnEndSystemTracing(

[sky, 2013/08/20 14:36:09]

One more. Is this part of TraceSubscriber? If so, remove 38 and add OVERRIDE. If
not, does it need to be public and virtual? Also, please document it (assuming
it isn't an OVERRIDE).

[DaveMoore, 2013/08/20 14:58:00]

Done.

+    const scoped_refptr<base::RefCountedString>& events_str_ptr);

[sky, 2013/08/20 14:36:09]

nit: two more spaces here.

[DaveMoore, 2013/08/20 14:58:00]

Done.

+
  private:
-  scoped_refptr<TraceSubscriberStdioImpl> impl_;
+  class TraceSubscriberStdioWorker;
+  scoped_refptr<TraceSubscriberStdioWorker> worker_;
   DISALLOW_COPY_AND_ASSIGN(TraceSubscriberStdio);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_TRACING_TRACE_SUBSCRIBER_STDIO_H_