Update NetLog to be thread safe.

chrome/browser/browser_process_impl.h

Index: chrome/browser/browser_process_impl.h
===================================================================
--- chrome/browser/browser_process_impl.h	(revision 67848)
+++ chrome/browser/browser_process_impl.h	(working copy)
@@ -24,6 +24,7 @@
 #include "chrome/browser/tab_contents/thumbnail_generator.h"
 #include "ipc/ipc_message.h"
 
+class ChromeNetLog;
 class CommandLine;
 class DebuggerWrapper;
 class FilePath;
@@ -211,6 +212,9 @@
   // notifications are properly added and removed.
   PrefChangeRegistrar pref_change_registrar_;
 
+  // Lives here so can safely log events on shutdown.
+  scoped_ptr<ChromeNetLog> net_log_;
+
 #if (defined(OS_WIN) || defined(OS_LINUX)) && !defined(OS_CHROMEOS)
   base::RepeatingTimer<BrowserProcessImpl> autoupdate_timer_;