headless: Add support for net logging

headless/lib/browser/headless_net_log.h

Index: headless/lib/browser/headless_net_log.h
diff --git a/headless/lib/browser/headless_net_log.h b/headless/lib/browser/headless_net_log.h
new file mode 100644
index 0000000000000000000000000000000000000000..ac33ee5ae6bc0bcb9d5d278c61cdbcb04f6c0624
--- /dev/null
+++ b/headless/lib/browser/headless_net_log.h
@@ -0,0 +1,33 @@
+// Copyright 2017 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 HEADLESS_LIB_BROWSER_HEADLESS_NET_LOG_H_
+#define HEADLESS_LIB_BROWSER_HEADLESS_NET_LOG_H_
+
+#include <memory>
+#include <string>
+
+#include "base/macros.h"
+#include "net/log/write_to_file_net_log_observer.h"
+
+namespace base {
+class FilePath;
+}
+
+namespace headless {
+
+class HeadlessNetLog : public net::NetLog {
+ public:
+  explicit HeadlessNetLog(const base::FilePath& log_path);
+  ~HeadlessNetLog() override;
+
+ private:
+  std::unique_ptr<net::WriteToFileNetLogObserver> write_to_file_observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(HeadlessNetLog);
+};
+
+}  // namespace headless
+
+#endif  // HEADLESS_LIB_BROWSER_HEADLESS_NET_LOG_H_