Mojo C++ bindings: remove the lock in MultiplexRouter if it only serves a single interface.

mojo/public/cpp/bindings/tests/bindings_perftest.cc

Index: mojo/public/cpp/bindings/tests/bindings_perftest.cc
diff --git a/mojo/public/cpp/bindings/tests/bindings_perftest.cc b/mojo/public/cpp/bindings/tests/bindings_perftest.cc
index 00e56941454aad5f5e60d1e92c06003bf4c363a6..35b41d24bf4fdc202c06f7b54e08f46d8e826373 100644
--- a/mojo/public/cpp/bindings/tests/bindings_perftest.cc
+++ b/mojo/public/cpp/bindings/tests/bindings_perftest.cc
@@ -217,11 +217,13 @@ TEST_F(MojoBindingsPerftest, RouterPingPong) {
 TEST_F(MojoBindingsPerftest, MultiplexRouterPingPong) {
   MessagePipe pipe;
   scoped_refptr<internal::MultiplexRouter> router0(
-      new internal::MultiplexRouter(true, std::move(pipe.handle0),
-                                    base::ThreadTaskRunnerHandle::Get()));
+      new internal::MultiplexRouter(std::move(pipe.handle0),
+                                    internal::MultiplexRouter::SINGLE_INTERFACE,
+                                    true, base::ThreadTaskRunnerHandle::Get()));
   scoped_refptr<internal::MultiplexRouter> router1(
-      new internal::MultiplexRouter(false, std::move(pipe.handle1),
-                                    base::ThreadTaskRunnerHandle::Get()));
+      new internal::MultiplexRouter(
+          std::move(pipe.handle1), internal::MultiplexRouter::SINGLE_INTERFACE,
+          false, base::ThreadTaskRunnerHandle::Get()));
 
   PingPongPaddle paddle0(nullptr);
   PingPongPaddle paddle1(nullptr);
@@ -302,7 +304,8 @@ TEST_F(MojoBindingsPerftest, RouterDispatchCost) {
 TEST_F(MojoBindingsPerftest, MultiplexRouterDispatchCost) {
   MessagePipe pipe;
   scoped_refptr<internal::MultiplexRouter> router(new internal::MultiplexRouter(
-      true, std::move(pipe.handle0), base::ThreadTaskRunnerHandle::Get()));
+      std::move(pipe.handle0), internal::MultiplexRouter::SINGLE_INTERFACE,
+      true, base::ThreadTaskRunnerHandle::Get()));
   CounterReceiver receiver;
   InterfaceEndpointClient client(
       router->CreateLocalEndpointHandle(kMasterInterfaceId), &receiver, nullptr,