support multiple log message handlers in base/logging.h

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 252df3da7c5b61499a37109909f392706885147d..3effb5d48f103612e3be6c4e16d0cabb2da31b91 100644
--- a/ios/chrome/browser/crash_report/breakpad_helper.mm
+++ b/ios/chrome/browser/crash_report/breakpad_helper.mm
@@ -78,11 +78,10 @@ void ClearCrashKeyValueImpl(const base::StringPiece& key) {
   RemoveReportParameter(base::SysUTF8ToNSString(key.as_string()));
 }
 
-// Callback for logging::SetLogMessageHandler
+// Callback for logging::AddLogMessageHandler
 bool FatalMessageHandler(int severity,
-                         const char* file,
+                         const std::string& file,
                          int line,
-                         size_t message_start,
                          const std::string& str) {
   // Do not handle non-FATAL.
   if (severity != logging::LOG_FATAL)
@@ -99,15 +98,16 @@ bool FatalMessageHandler(int severity,
   base::AutoReset<bool> guard(&guarded, true);
 
   // Only log last path component.  This matches logging.cc.
-  if (file) {
-    const char* slash = strrchr(file, '/');
-    if (slash)
-      file = slash + 1;
-  }
+  size_t last_slash = file.rfind('/');
+  if (last_slash == file.npos)
+    last_slash = 0;
+  else
+    last_slash++;
 
   NSString* fatal_key = @"LOG_FATAL";
-  NSString* fatal_value = [NSString
-      stringWithFormat:@"%s:%d: %s", file, line, str.c_str() + message_start];
+  NSString* fatal_value =
+      [NSString stringWithFormat:@"%s:%d: %s", file.substr(last_slash).c_str(),
+                                 line, str.c_str()];
   AddReportParameter(fatal_key, fatal_value, true);
 
   // Rather than including the code to force the crash here, allow the
@@ -130,7 +130,7 @@ void Start(const std::string& channel_name) {
   [[BreakpadController sharedInstance] start:YES];
   base::debug::SetCrashKeyReportingFunctions(&SetCrashKeyValueImpl,
                                              &ClearCrashKeyValueImpl);
-  logging::SetLogMessageHandler(&FatalMessageHandler);
+  logging::AddLogMessageHandler(&FatalMessageHandler);
   g_crash_reporter_enabled = true;
   // Register channel information.
   if (channel_name.length()) {