Only set File::[tracing_]path_ when file tracing is enabled.

base/files/file.cc

 // Copyright (c) 2011 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.
 
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/files/file_tracing.h"
 #include "base/metrics/histogram.h"
 #include "base/timer/elapsed_timer.h"
 
@@ skipping 72 matching lines @@
   }
   return *this;
 }
 
 #if !defined(OS_NACL)
 void File::Initialize(const FilePath& path, uint32 flags) {
   if (path.ReferencesParent()) {
     error_details_ = FILE_ERROR_ACCESS_DENIED;
     return;
   }
-  path_ = path;
+  if (FileTracing::IsCategoryEnabled())
+    path_ = path;
   SCOPED_FILE_TRACE("Initialize");
   DoInitialize(flags);
 }
 #endif
 
 std::string File::ErrorToString(Error error) {
   switch (error) {
     case FILE_OK:
       return "FILE_OK";
     case FILE_ERROR_FAILED:
@@ skipping 38 matching lines @@
 
 bool File::Flush() {
   ElapsedTimer timer;
   SCOPED_FILE_TRACE("Flush");
   bool return_value = DoFlush();
   UMA_HISTOGRAM_TIMES("PlatformFile.FlushTime", timer.Elapsed());
   return return_value;
 }
 
 }  // namespace base