support multiple log message handlers in base/logging.h

base/logging_win.cc

Index: base/logging_win.cc
diff --git a/base/logging_win.cc b/base/logging_win.cc
index 319ae8a9d38186aa7ffc6466f574c2a795a1832c..6a86e51c40bf2a664d6267aa2a3a3266b6210b52 100644
--- a/base/logging_win.cc
+++ b/base/logging_win.cc
@@ -23,8 +23,9 @@ LogEventProvider* LogEventProvider::GetInstance() {
 }
 
 bool LogEventProvider::LogMessage(logging::LogSeverity severity,
-    const char* file, int line, size_t message_start,
-    const std::string& message) {
+                                  const std::string& file,
+                                  int line,
+                                  const std::string& message) {
   EtwEventLevel level = TRACE_LEVEL_NONE;
 
   // Convert the log severity to the most appropriate ETW trace level.
@@ -56,8 +57,7 @@ bool LogEventProvider::LogMessage(logging::LogSeverity severity,
   // And now log the event.
   if (provider->enable_flags() & ENABLE_LOG_MESSAGE_ONLY) {
     EtwMofEvent<1> event(kLogEventId, LOG_MESSAGE, level);
-    event.SetField(0, message.length() + 1 - message_start,
-        message.c_str() + message_start);
+    event.SetField(0, message.length() + 1, message.c_str());
 
     provider->Log(event.get());
   } else {
@@ -71,8 +71,6 @@ bool LogEventProvider::LogMessage(logging::LogSeverity severity,
       depth = CaptureStackBackTrace(2, kMaxBacktraceDepth, backtrace, NULL);
 
     EtwMofEvent<5> event(kLogEventId, LOG_MESSAGE_FULL, level);
-    if (file == NULL)
-      file = "";
 
     // Add the stack trace.
     event.SetField(0, sizeof(depth), &depth);
@@ -80,10 +78,9 @@ bool LogEventProvider::LogMessage(logging::LogSeverity severity,
     // The line.
     event.SetField(2, sizeof(line), &line);
     // The file.
-    event.SetField(3, strlen(file) + 1, file);
+    event.SetField(3, file.length() + 1, file.c_str());
     // And finally the message.
-    event.SetField(4, message.length() + 1 - message_start,
-        message.c_str() + message_start);
+    event.SetField(4, message.length() + 1, message.c_str());
 
     provider->Log(event.get());
   }
@@ -102,7 +99,7 @@ void LogEventProvider::Initialize(const GUID& provider_name) {
   provider->Register();
 
   // Register our message handler with logging.
-  SetLogMessageHandler(LogMessage);
+  AddLogMessageHandler(LogMessage);
 }
 
 void LogEventProvider::Uninitialize() {