Use NESTABLE_ASYNC APIs to get NetLog data into Tracing

net/base/trace_net_log_observer.cc

+// 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.
+
+#include "net/base/trace_net_log_observer.h"
+
+#include <stdio.h>
+
+#include <string>
+
+#include "base/debug/trace_event.h"
+#include "base/json/json_writer.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/values.h"
+#include "net/base/net_log.h"
+
+namespace net {
+
+namespace {
+
+class TracedValue : public base::debug::ConvertableToTraceFormat {
+ public:
+  explicit TracedValue(scoped_ptr<base::Value> value) : value_(value.Pass()) {}
+
+ private:
+  virtual ~TracedValue() {}
+
+  virtual void AppendAsTraceFormat(std::string* out) const OVERRIDE {
+    if (value_) {
+      std::string tmp;
+      base::JSONWriter::Write(value_.get(), &tmp);
+      *out += tmp;
+    } else {
+      *out += "\"\"";
+    }
+  }
+
+ private:
+  scoped_ptr<base::Value> value_;
+};
+
+}  // namespace
+
+TraceNetLogObserver::TraceNetLogObserver() : net_log_to_watch_(NULL) {
+}
+
+TraceNetLogObserver::~TraceNetLogObserver() {
+  DCHECK(!net_log_to_watch_);
+  DCHECK(!net_log());
+}
+
+void TraceNetLogObserver::OnAddEntry(const NetLog::Entry& entry) {
+  scoped_ptr<base::Value> params(entry.ParametersToValue());
+  switch (entry.phase()) {
+    case NetLog::PHASE_BEGIN:
+      TRACE_EVENT_NET_LOG_BEGIN(
+          "netlog", NetLog::EventTypeToString(entry.type()), entry.source().id,
+          "source_type", NetLog::SourceTypeToString(entry.source().type),
+          "params", scoped_refptr<base::debug::ConvertableToTraceFormat>(
+              new TracedValue(params.Pass())));
+      break;
+    case NetLog::PHASE_END:
+      TRACE_EVENT_NET_LOG_END(
+          "netlog", NetLog::EventTypeToString(entry.type()), entry.source().id,
+          "source_type", NetLog::SourceTypeToString(entry.source().type),
+          "params", scoped_refptr<base::debug::ConvertableToTraceFormat>(
+              new TracedValue(params.Pass())));
+      break;
+    case NetLog::PHASE_NONE:
+      TRACE_EVENT_NET_LOG_INSTANT(
+          "netlog", NetLog::EventTypeToString(entry.type()), entry.source().id,
+          "source_type", NetLog::SourceTypeToString(entry.source().type),
+          "params", scoped_refptr<base::debug::ConvertableToTraceFormat>(
+              new TracedValue(params.Pass())));
+      break;
+  }
+}
+
+void TraceNetLogObserver::WatchForTraceStart(NetLog* net_log) {

[mmenke, 2014/08/27 19:03:14]

DCHECK(!net_log_to_watch_);?

Otherwise, we'd end up adding ourselves as an EnabledStateObserver twice.

[mmenke, 2014/08/27 19:03:14]

DCHECK(!net_log());

[xunjieli, 2014/09/02 16:37:33]

Done.

[xunjieli, 2014/09/02 16:37:33]

Done.

+  net_log_to_watch_ = net_log;
+  base::debug::TraceLog::GetInstance()->AddEnabledStateObserver(this);
+}
+
+void TraceNetLogObserver::StopWatchForTraceStart() {
+  // Should only stop if is currently watching.
+  DCHECK(net_log_to_watch_);
+  base::debug::TraceLog::GetInstance()->RemoveEnabledStateObserver(this);
+  if (net_log())
+    net_log()->RemoveThreadSafeObserver(this);
+  net_log_to_watch_ = NULL;
+}
+
+void TraceNetLogObserver::OnTraceLogEnabled() {
+  net_log_to_watch_->AddThreadSafeObserver(this,
+                                           NetLog::LOG_STRIP_PRIVATE_DATA);
+}
+
+void TraceNetLogObserver::OnTraceLogDisabled() {
+  if (net_log())
+    net_log()->RemoveThreadSafeObserver(this);
+}
+
+}  // namespace net