Display the proxy PAC javascript errors in the NetLog....

net/base/forwarding_net_log.h

+// Copyright (c) 2010 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_FORWARDING_NET_LOG_H_
+#define NET_BASE_FORWARDING_NET_LOG_H_
+
+#include "base/basictypes.h"
+#include "net/base/net_log.h"
+
+class MessageLoop;
+
+namespace net {
+
+// ForwardingNetLog is a wrapper that can be called on any thread, and will
+// forward any calls to NetLog::AddEntry() over to |impl| on the specified
+// message loop.
+//
+// This allows using a non-threadsafe NetLog implementation from another
+// thread.
+//
+// TODO(eroman): Explore making NetLog threadsafe and obviating the need
+//               for this class.
+class ForwardingNetLog : public NetLog {
+ public:
+  // Both |impl| and |loop| must outlive the lifetime of this instance.
+  // |impl| will be operated only from |loop|.
+  ForwardingNetLog(NetLog* impl, MessageLoop* loop);
+
+  // On destruction any outstanding call to AddEntry() which didn't make
+  // it to |loop| yet will be cancelled.
+  ~ForwardingNetLog();
+
+  // NetLog methods:
+  virtual void AddEntry(EventType type,
+                        const base::TimeTicks& time,
+                        const Source& source,
+                        EventPhase phase,
+                        EventParameters* params);
+  virtual uint32 NextID();
+  virtual bool HasListener() const;
+
+ private:
+  class Core;
+  scoped_refptr<Core> core_;
+
+  DISALLOW_COPY_AND_ASSIGN(ForwardingNetLog);
+};
+
+}  // namespace net
+
+#endif  // NET_BASE_FORWARDING_NET_LOG_H_
+