Allow multiple logging::LogMessage{Handler,Listener}s

base/logging_win.cc

Index: base/logging_win.cc
diff --git a/base/logging_win.cc b/base/logging_win.cc
index 319ae8a9d38186aa7ffc6466f574c2a795a1832c..9aab9b08f521dc2afe54b0c5335a6fb5049d34b6 100644
--- a/base/logging_win.cc
+++ b/base/logging_win.cc
@@ -88,7 +88,8 @@ bool LogEventProvider::LogMessage(logging::LogSeverity severity,
     provider->Log(event.get());
   }
 
-  // Don't increase verbosity in other log destinations.
+  // Don't increase verbosity in other log destinations below this handler
+  // in the handler stack.
   if (severity < provider->old_log_level_)
     return true;
 
@@ -102,11 +103,12 @@ void LogEventProvider::Initialize(const GUID& provider_name) {
   provider->Register();
 
   // Register our message handler with logging.
-  SetLogMessageHandler(LogMessage);
+  PushLogMessageHandler(LogMessage);
 }
 
 void LogEventProvider::Uninitialize() {
   LogEventProvider::GetInstance()->Unregister();
+  PopLogMessageHandler(LogMessage);
 }
 
 void LogEventProvider::OnEventsEnabled() {