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

components/proximity_auth/logging/logging_unittest.cc

 // Copyright 2015 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 "components/proximity_auth/logging/logging.h"
 
 #include <stddef.h>
 
 #include "base/lazy_instance.h"
 #include "base/numerics/safe_conversions.h"
@@ skipping 19 matching lines @@
                               size_t message_start,
                               const std::string& str) {
   g_standard_logs.Get().push_back(str);
   return true;
 }
 
 }  // namespace
 
 class ProximityAuthLoggingTest : public testing::Test {
  public:
-  ProximityAuthLoggingTest() : previous_handler_(NULL) {}
-
   void SetUp() override {
     LogBuffer::GetInstance()->Clear();
     g_standard_logs.Get().clear();
 
-    previous_handler_ = logging::GetLogMessageHandler();
-    logging::SetLogMessageHandler(&HandleStandardLogMessage);
+    logging::PushLogMessageHandler(&HandleStandardLogMessage);
   }
 
-  void TearDown() override { logging::SetLogMessageHandler(previous_handler_); }
-
- private:
-  logging::LogMessageHandlerFunction previous_handler_;
+  void TearDown() override { logging::PopLogMessageHandler(); }
 };
 
 TEST_F(ProximityAuthLoggingTest, LogsSavedToBuffer) {
   int base_line_number = __LINE__;
   PA_LOG(INFO) << kLog1;
   PA_LOG(WARNING) << kLog2;
   PA_LOG(ERROR) << kLog3;
 
   auto logs = LogBuffer::GetInstance()->logs();
   ASSERT_EQ(3u, logs->size());
@@ skipping 46 matching lines @@
   PA_LOG(WARNING) << kLog2;
   PA_LOG(ERROR) << kLog3;
 
   ASSERT_EQ(3u, g_standard_logs.Get().size());
   EXPECT_NE(std::string::npos, g_standard_logs.Get()[0].find(kLog1));
   EXPECT_NE(std::string::npos, g_standard_logs.Get()[1].find(kLog2));
   EXPECT_NE(std::string::npos, g_standard_logs.Get()[2].find(kLog3));
 }
 
 }  // namespace proximity_auth