Update from https://crrev.com/305340

net/base/capturing_net_log_observer.h

+// 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_CAPTURING_NET_LOG_OBSERVER_H_
+#define NET_BASE_CAPTURING_NET_LOG_OBSERVER_H_
+
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/synchronization/lock.h"
+#include "net/base/captured_net_log_entry.h"
+#include "net/base/net_log.h"
+
+namespace base {
+class DictionaryValue;
+class ListValue;
+}
+
+namespace net {
+
+// CapturingNetLogObserver is an implementation of NetLog::ThreadSafeObserver
+// that saves messages to a bounded buffer. It is intended for testing only,
+// and is part of the net_test_support project.
+class CapturingNetLogObserver : public NetLog::ThreadSafeObserver {
+ public:
+  CapturingNetLogObserver();
+  ~CapturingNetLogObserver() override;
+
+  // Returns the list of all entries in the log.
+  void GetEntries(CapturedNetLogEntry::List* entry_list) const;
+
+  // Fills |entry_list| with all entries in the log from the specified Source.
+  void GetEntriesForSource(NetLog::Source source,
+                           CapturedNetLogEntry::List* entry_list) const;
+
+  // Returns number of entries in the log.
+  size_t GetSize() const;
+
+  void Clear();
+
+ private:
+  // ThreadSafeObserver implementation:
+  void OnAddEntry(const NetLog::Entry& entry) override;
+
+  // Needs to be "mutable" so can use it in GetEntries().
+  mutable base::Lock lock_;
+
+  CapturedNetLogEntry::List captured_entries_;
+
+  DISALLOW_COPY_AND_ASSIGN(CapturingNetLogObserver);
+};
+
+}  // namespace net
+
+#endif  // NET_BASE_CAPTURING_NET_LOG_OBSERVER_H_