Use NESTABLE_ASYNC APIs to get NetLog data into Tracing

chrome/browser/net/chrome_net_log.h

Index: chrome/browser/net/chrome_net_log.h
diff --git a/chrome/browser/net/chrome_net_log.h b/chrome/browser/net/chrome_net_log.h
index 4114868af29179aaafdbbec85ad8a2d7d71ecd22..c0b2ee6196dd381e8130cbb238603e2b047c2fc5 100644
--- a/chrome/browser/net/chrome_net_log.h
+++ b/chrome/browser/net/chrome_net_log.h
@@ -13,6 +13,7 @@
 
 namespace net {
 class NetLogLogger;
+class TraceNetLogObserver;
 }
 
 class NetLogTempFile;
@@ -32,6 +33,8 @@ class ChromeNetLog : public net::NetLog {
   scoped_ptr<net::NetLogLogger> net_log_logger_;
   scoped_ptr<NetLogTempFile> net_log_temp_file_;
 
+  scoped_ptr<net::TraceNetLogObserver> trace_net_log_observer_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeNetLog);
 };