Use NESTABLE_ASYNC APIs to get NetLog data into Tracing

net/base/trace_net_log_observer.h

Index: net/base/trace_net_log_observer.h
diff --git a/net/base/trace_net_log_observer.h b/net/base/trace_net_log_observer.h
new file mode 100644
index 0000000000000000000000000000000000000000..1b05e9084c0246e32abf996be9b409f07c92e5fb
--- /dev/null
+++ b/net/base/trace_net_log_observer.h
@@ -0,0 +1,50 @@
+// Copyright 2014 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 NET_BASE_TRACE_NET_LOG_OBSERVER_H_
+#define NET_BASE_TRACE_NET_LOG_OBSERVER_H_
+
+#include "base/debug/trace_event_impl.h"
+#include "base/macros.h"
+#include "net/base/net_export.h"
+#include "net/base/net_log.h"
+
+

[mmenke, 2014/08/21 15:35:40]

nit:  Remove above blank line.

[xunjieli, 2014/08/22 17:20:10]

Done.

+namespace net {
+
+class NET_EXPORT TraceNetLogObserver
+  : public NetLog::ThreadSafeObserver,
+    public base::debug::TraceLog::EnabledStateObserver {

[mmenke, 2014/08/21 15:35:40]

nit:  Above two lines should be indented two more.

[xunjieli, 2014/08/22 17:20:10]

Done. Thanks!

+ public:
+  TraceNetLogObserver();
+  virtual ~TraceNetLogObserver();
+
+  void StartObserving(NetLog* net_log);
+
+  // Stops observing net_log().  Must already be watching.
+  void StopObserving();

[mmenke, 2014/08/21 15:35:40]

Neither of these two functions need to be public.  Actually, could just get rid
of them, since they're only one line.

[xunjieli, 2014/08/22 17:20:10]

Done. Thanks! Good idea!

+
+  // net::NetLog::ThreadSafeObserver implementation:
+  virtual void OnAddEntry(const NetLog::Entry& entry) OVERRIDE;
+
+  void WatchForTraceStart(NetLog* net_log);
+
+  void StopWatchForTraceStart();
+
+  // base::debug::TraceLog::EnabledStateChangedObserver implementation:
+  virtual void OnTraceLogEnabled() OVERRIDE;
+  virtual void OnTraceLogDisabled() OVERRIDE;
+
+ private:
+  // The LogLevel to log at.
+  NetLog::LogLevel log_level_;

[mmenke, 2014/08/21 15:35:40]

Let's just get rid of this, for now, until we need.

[xunjieli, 2014/08/22 17:20:10]

Done.

+
+  NetLog* net_log_to_watch_;
+
+  DISALLOW_COPY_AND_ASSIGN(TraceNetLogObserver);
+};
+
+}  // namespace net
+
+#endif  // NET_BASE_TRACE_NET_LOG_OBSERVER_H_