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

ios/chrome/browser/crash_report/breakpad_helper.mm

Index: ios/chrome/browser/crash_report/breakpad_helper.mm
diff --git a/ios/chrome/browser/crash_report/breakpad_helper.mm b/ios/chrome/browser/crash_report/breakpad_helper.mm
index 4ae4326a950f17503efd274a8578d9e974dc80fd..aa9b0714c18602b1399c80458567a8b5bd159f64 100644
--- a/ios/chrome/browser/crash_report/breakpad_helper.mm
+++ b/ios/chrome/browser/crash_report/breakpad_helper.mm
@@ -82,15 +82,22 @@ void ClearCrashKeyValueImpl(const base::StringPiece& key) {
   RemoveReportParameter(base::SysUTF8ToNSString(key.as_string()));
 }
 
-// Callback for logging::SetLogMessageHandler
-bool FatalMessageHandler(int severity,
-                         const char* file,
-                         int line,
-                         size_t message_start,
-                         const std::string& str) {
+class FatalMessageListener : logging::LogMessageListener {
+  void OnMessage(int severity,
+                 const char* file,
+                 int line,
+                 size_t message_start,
+                 const std::string& str) override;
+};
+
+void FatalMessageListener::OnMessage(int severity,
+                                     const char* file,
+                                     int line,
+                                     size_t message_start,
+                                     const std::string& str) {
   // Do not handle non-FATAL.
   if (severity != logging::LOG_FATAL)
-    return false;
+    return;
 
   // In case of OOM condition, this code could be reentered when
   // constructing and storing the key.  Using a static is not
@@ -98,7 +105,7 @@ bool FatalMessageHandler(int severity,
   // fatal crash at the same time, this should work.
   static bool guarded = false;
   if (guarded)
-    return false;
+    return;
 
   base::AutoReset<bool> guard(&guarded, true);
 
@@ -116,7 +123,6 @@ bool FatalMessageHandler(int severity,
 
   // Rather than including the code to force the crash here, allow the
   // caller to do it.
-  return false;
 }
 
 // Caches the uploading flag in NSUserDefaults, so that we can access the value
@@ -134,7 +140,10 @@ void Start(const std::string& channel_name) {
   [[BreakpadController sharedInstance] start:YES];
   base::debug::SetCrashKeyReportingFunctions(&SetCrashKeyValueImpl,
                                              &ClearCrashKeyValueImpl);
-  logging::SetLogMessageHandler(&FatalMessageHandler);
+  // Intentionally leak the listener.
+  auto* listener = new FatalMessageListener();
+  CHECK(listener);
+
   g_crash_reporter_enabled = true;
   // Register channel information.
   if (channel_name.length()) {