support multiple log message handlers in base/logging.h

remoting/host/native_messaging/log_message_handler.h

 // Copyright 2015 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 REMOTING_HOST_NATIVE_MESSAGIN_LOG_HANDLER_H_
 #define REMOTING_HOST_NATIVE_MESSAGIN_LOG_HANDLER_H_
 
 #include <stddef.h>
 
 #include <memory>
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/values.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace remoting {
 
-// Helper class for logging::SetLogMessageHandler to deliver log messages to
+// Helper class for logging::AddLogMessageHandler to deliver log messages to
 // a consistent thread in a thread-safe way and in a format suitable for sending
 // over a Native Messaging channel.
 class LogMessageHandler {
  public:
   typedef base::Callback<void(std::unique_ptr<base::Value> message)> Delegate;
 
   explicit LogMessageHandler(const Delegate& delegate);
   ~LogMessageHandler();
 
   static const char* kDebugMessageTypeName;
 
  private:
   static bool OnLogMessage(
       int severity, const char* file, int line,
       size_t message_start, const std::string& str);
   void PostLogMessageToCorrectThread(
       int severity, const char* file, int line,
       size_t message_start, const std::string& str);
   void SendLogMessageToClient(
       int severity, const char* file, int line,
       size_t message_start, const std::string& str);
 
   Delegate delegate_;
   bool suppress_logging_;
   scoped_refptr<base::SingleThreadTaskRunner> caller_task_runner_;
-  logging::LogMessageHandlerFunction previous_log_message_handler_;
   base::WeakPtrFactory<LogMessageHandler> weak_ptr_factory_;
 };
 
 }  // namespace remoting
 
 #endif