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

base/test/mock_log.cc

Index: base/test/mock_log.cc
diff --git a/base/test/mock_log.cc b/base/test/mock_log.cc
index a09000d8ed7f9e3080ff06a64cb060c76fa591f6..eb74352a0c121608e77121c929c2d0f7951e8835 100644
--- a/base/test/mock_log.cc
+++ b/base/test/mock_log.cc
@@ -31,8 +31,7 @@ void MockLog::StartCapturingLogs() {
 
   is_capturing_logs_ = true;
   g_instance_ = this;
-  previous_handler_ = logging::GetLogMessageHandler();
-  logging::SetLogMessageHandler(LogMessageHandler);
+  logging::AddLogMessageListener(LogMessageListener);
 }
 
 void MockLog::StopCapturingLogs() {
@@ -45,16 +44,16 @@ void MockLog::StopCapturingLogs() {
   RAW_CHECK(g_instance_ == this);
 
   is_capturing_logs_ = false;
-  logging::SetLogMessageHandler(previous_handler_);
+  logging::RemoveLogMessageListener(LogMessageListener);
   g_instance_ = nullptr;
 }
 
 // static
-bool MockLog::LogMessageHandler(int severity,
-                                const char* file,
-                                int line,
-                                size_t message_start,
-                                const std::string& str) {
+void MockLog::LogMessageListener(int severity,
+                                 const char* file,
+                                 int line,
+                                 size_t message_start,
+                                 const std::string& str) {
   // gMock guarantees thread-safety for calling a mocked method
   // (https://github.com/google/googlemock/blob/master/googlemock/docs/CookBook.md#using-google-mock-and-threads)
   // but we also need to make sure that Start/StopCapturingLogs are synchronized