Add --trace-rotate-startup-file option and store unsaved trace data on exit.

content/browser/browser_shutdown_profile_dumper.h

 // Copyright 2013 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_BROWSER_SHUTDOWN_PROFILE_DUMPER_H_
 #define CONTENT_BROWSER_BROWSER_SHUTDOWN_PROFILE_DUMPER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/ref_counted_memory.h"
 #include "content/common/content_export.h"
 
 namespace base {
 class FilePath;
 class WaitableEvent;
 }
 
 namespace content {
 
 // This class is intended to dump the tracing results of the shutdown process
 // to a file before the browser process exits.
 // It will save the file either into the command line passed
 // "--trace-shutdown-file=<name>" parameter - or - to "chrometrace.log" in the
 // current directory.
 // Use the class with a scoped_ptr to get files written in the destructor.
 // Note that we cannot use the asynchronous file writer since the
 // |SequencedWorkerPool| will get killed in the shutdown process.
 class BrowserShutdownProfileDumper {
  public:
-  BrowserShutdownProfileDumper();
+  explicit BrowserShutdownProfileDumper(const base::FilePath& dump_file_name);
 
   ~BrowserShutdownProfileDumper();
 
  private:
   // Writes all traces which happened to disk.
-  void WriteTracesToDisc(const base::FilePath& file_name);
+  void WriteTracesToDisc();
 
   void EndTraceAndFlush(base::WaitableEvent* flush_complete_event);
 
-  // Returns the file name where we should save the trace dump to.
-  base::FilePath GetFileName();
-
   // The callback for the |TraceLog::Flush| function. It saves all traces to
   // disc.
   void WriteTraceDataCollected(
       base::WaitableEvent* flush_complete_event,
       const scoped_refptr<base::RefCountedString>& events_str,
       bool has_more_events);
 
   // Returns true if the dump file is valid.
   bool IsFileValid();
 
   // Writes a string to the dump file.
   void WriteString(const std::string& string);
 
   // Write a buffer to the dump file.
   void WriteChars(const char* chars, size_t size);
 
   // Closes the dump file.
   void CloseFile();
 
+  // The name of the dump file.
+  base::FilePath dump_file_name_;
+
   // The number of blocks we have already written.
   int blocks_;
   // For dumping the content to disc.
   FILE* dump_file_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserShutdownProfileDumper);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_BROWSER_SHUTDOWN_PROFILE_DUMPER_H_