Tag some of Mojo heap allocations for the heap profiler.

mojo/public/cpp/bindings/lib/multiplex_router.cc

Index: mojo/public/cpp/bindings/lib/multiplex_router.cc
diff --git a/mojo/public/cpp/bindings/lib/multiplex_router.cc b/mojo/public/cpp/bindings/lib/multiplex_router.cc
index 14ea64740756a9377829c23512a2eb1b7b457603..fd68d86e59973bdc0d86e33c6c4d48e0b57df85b 100644
--- a/mojo/public/cpp/bindings/lib/multiplex_router.cc
+++ b/mojo/public/cpp/bindings/lib/multiplex_router.cc
@@ -350,11 +350,13 @@ MultiplexRouter::~MultiplexRouter() {
   DCHECK(endpoints_.empty());
 }
 
-void MultiplexRouter::SetMasterInterfaceName(const std::string& name) {
+void MultiplexRouter::SetMasterInterfaceName(const char* name) {
   DCHECK(thread_checker_.CalledOnValidThread());
-  header_validator_->SetDescription(name + " [master] MessageHeaderValidator");
+  header_validator_->SetDescription(
+      std::string(name) + " [master] MessageHeaderValidator");
   control_message_handler_.SetDescription(
-      name + " [master] PipeControlMessageHandler");
+      std::string(name) + " [master] PipeControlMessageHandler");
+  connector_.SetWatcherHeapProfilerTag(name);
 }
 
 void MultiplexRouter::CreateEndpointHandlePair(