InterfacePtr: not configure proxy until actual read/write is needed.

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

Index: mojo/public/cpp/bindings/tests/validation_unittest.cc
diff --git a/mojo/public/cpp/bindings/tests/validation_unittest.cc b/mojo/public/cpp/bindings/tests/validation_unittest.cc
index 0b22720de5839ce4fda4a647e4685f1ad4ce57b4..92692128c87828151b1835c7241f86a2900f284e 100644
--- a/mojo/public/cpp/bindings/tests/validation_unittest.cc
+++ b/mojo/public/cpp/bindings/tests/validation_unittest.cc
@@ -406,7 +406,7 @@ TEST_F(ValidationIntegrationTest, InterfacePtr) {
   IntegrationTestInterface2Ptr interface2_ptr =
       MakeProxy<IntegrationTestInterface2>(testee_endpoint().Pass());
   interface2_ptr.set_client(&interface1_client);
-  interface2_ptr.internal_state()->router()->EnableTestingMode();
+  interface2_ptr.internal_state()->router_for_testing()->EnableTestingMode();
 
   RunValidationTests("integration_", test_message_receiver());
 }