support multiple log message handlers in base/logging.h

remoting/host/native_messaging/log_message_handler.cc

Index: remoting/host/native_messaging/log_message_handler.cc
diff --git a/remoting/host/native_messaging/log_message_handler.cc b/remoting/host/native_messaging/log_message_handler.cc
index 70f744b87e87b1d5ddcd84c486a7b06c720dc715..9f532456c9a2b89831ce63fc686eaa9abb2d0c2a 100644
--- a/remoting/host/native_messaging/log_message_handler.cc
+++ b/remoting/host/native_messaging/log_message_handler.cc
@@ -37,18 +37,13 @@ LogMessageHandler::LogMessageHandler(
     LOG(FATAL) << "LogMessageHandler is already registered. Only one instance "
                << "per process is allowed.";
   }
-  previous_log_message_handler_ = logging::GetLogMessageHandler();
-  logging::SetLogMessageHandler(&LogMessageHandler::OnLogMessage);
+  logging::AddLogMessageHandler(&LogMessageHandler::OnLogMessage);
   g_log_message_handler = this;
 }
 
 LogMessageHandler::~LogMessageHandler() {
   base::AutoLock lock(g_log_message_handler_lock.Get());
-  if (logging::GetLogMessageHandler() != &LogMessageHandler::OnLogMessage) {
-    LOG(FATAL) << "LogMessageHandler is not the top-most message handler. "
-               << "Cannot unregister.";
-  }
-  logging::SetLogMessageHandler(previous_log_message_handler_);
+  logging::RemoveLogMessageHandler(&LogMessageHandler::OnLogMessage);
   g_log_message_handler = nullptr;
 }
 
@@ -58,23 +53,21 @@ const char* LogMessageHandler::kDebugMessageTypeName = "_debug_log";
 // static
 bool LogMessageHandler::OnLogMessage(
     logging::LogSeverity severity,
-    const char* file,
+    const std::string& file,
     int line,
-    size_t message_start,
     const std::string& str) {
   base::AutoLock lock(g_log_message_handler_lock.Get());
   if (g_log_message_handler) {
     g_log_message_handler->PostLogMessageToCorrectThread(
-        severity, file, line, message_start, str);
+        severity, file, line, str);
   }
   return false;
 }
 
 void LogMessageHandler::PostLogMessageToCorrectThread(
     logging::LogSeverity severity,
-    const char* file,
+    const std::string& file,
     int line,
-    size_t message_start,
     const std::string& str) {
   // Don't process this message if we're already logging and on the caller
   // thread. This guards against an infinite loop if any code called by this
@@ -93,14 +86,13 @@ void LogMessageHandler::PostLogMessageToCorrectThread(
       FROM_HERE,
       base::Bind(&LogMessageHandler::SendLogMessageToClient,
                  weak_ptr_factory_.GetWeakPtr(),
-                 severity, file, line, message_start, str));
+                 severity, file, line, str));
 }
 
 void LogMessageHandler::SendLogMessageToClient(
     logging::LogSeverity severity,
-    const char* file,
+    const std::string& file,
     int line,
-    size_t message_start,
     const std::string& str) {
   suppress_logging_ = true;