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

base/trace_event/trace_event_unittest.cc

 // Copyright (c) 2012 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.
 
 #include "base/trace_event/trace_event.h"
 
 #include <math.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 3019 matching lines @@
   BeginTrace();
   thread.task_runner()->PostTask(
       FROM_HERE, Bind(&TraceWithAllMacroVariants, &task_complete_event));
   task_complete_event.Wait();
   task_complete_event.Reset();
   EndTraceAndFlushInThreadWithMessageLoop();
   ValidateAllTraceMacrosCreatedData(trace_parsed_);
 }
 
 std::string* g_log_buffer = NULL;
-bool MockLogMessageHandler(int, const char*, int, size_t,
-                           const std::string& str) {
+void MockLogMessageListener(int, const char*, int, size_t,
+                            const std::string& str) {
   if (!g_log_buffer)
     g_log_buffer = new std::string();
   g_log_buffer->append(str);
-  return false;
 }
 
 TEST_F(TraceEventTestFixture, EchoToConsole) {
-  logging::LogMessageHandlerFunction old_log_message_handler =
-      logging::GetLogMessageHandler();
-  logging::SetLogMessageHandler(MockLogMessageHandler);
+  logging::ScopedLogMessageListener l(MockLogMessageListener);
 
   TraceLog::GetInstance()->SetEnabled(
       TraceConfig(kRecordAllCategoryFilter, ECHO_TO_CONSOLE),
       TraceLog::RECORDING_MODE);
   TRACE_EVENT_BEGIN0("a", "begin_end");
   {
     TRACE_EVENT0("b", "duration");
     TRACE_EVENT0("b1", "duration1");
   }
   TRACE_EVENT_INSTANT0("c", "instant", TRACE_EVENT_SCOPE_GLOBAL);
   TRACE_EVENT_END0("a", "begin_end");
 
   EXPECT_NE(std::string::npos, g_log_buffer->find("begin_end[a]\x1b"));
   EXPECT_NE(std::string::npos, g_log_buffer->find("| duration[b]\x1b"));
   EXPECT_NE(std::string::npos, g_log_buffer->find("| | duration1[b1]\x1b"));
   EXPECT_NE(std::string::npos, g_log_buffer->find("| | duration1[b1] ("));
   EXPECT_NE(std::string::npos, g_log_buffer->find("| duration[b] ("));
   EXPECT_NE(std::string::npos, g_log_buffer->find("| instant[c]\x1b"));
   EXPECT_NE(std::string::npos, g_log_buffer->find("begin_end[a] ("));
 
   EndTraceAndFlush();
   delete g_log_buffer;
-  logging::SetLogMessageHandler(old_log_message_handler);
   g_log_buffer = NULL;
 }
 
-bool LogMessageHandlerWithTraceEvent(int, const char*, int, size_t,
+void LogMessageListenerWithTraceEvent(int, const char*, int, size_t,
                                      const std::string&) {
   TRACE_EVENT0("log", "trace_event");
-  return false;
 }
 
 TEST_F(TraceEventTestFixture, EchoToConsoleTraceEventRecursion) {
-  logging::LogMessageHandlerFunction old_log_message_handler =
-      logging::GetLogMessageHandler();
-  logging::SetLogMessageHandler(LogMessageHandlerWithTraceEvent);
+  logging::ScopedLogMessageListener l(LogMessageListenerWithTraceEvent);
 
   TraceLog::GetInstance()->SetEnabled(
       TraceConfig(kRecordAllCategoryFilter, ECHO_TO_CONSOLE),
       TraceLog::RECORDING_MODE);
   {
     // This should not cause deadlock or infinite recursion.
     TRACE_EVENT0("b", "duration");
   }
 
   EndTraceAndFlush();
-  logging::SetLogMessageHandler(old_log_message_handler);
 }
 
 TEST_F(TraceEventTestFixture, TimeOffset) {
   BeginTrace();
   // Let TraceLog timer start from 0.
   TimeDelta time_offset = TimeTicks::Now() - TimeTicks();
   TraceLog::GetInstance()->SetTimeOffset(time_offset);
 
   {
     TRACE_EVENT0("all", "duration1");
@@ skipping 66 matching lines @@
 
 TEST_F(TraceEventTestFixture, ClockSyncEventsAreAlwaysAddedToTrace) {
   BeginSpecificTrace("-*");
   TRACE_EVENT_CLOCK_SYNC_RECEIVER(1);
   EndTraceAndFlush();
   EXPECT_TRUE(FindNamePhase("clock_sync", "c"));
 }
 
 }  // namespace trace_event
 }  // namespace base