Make sure channel-associated interface pointers are always safe to call.

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

Index: mojo/public/cpp/bindings/tests/associated_interface_unittest.cc
diff --git a/mojo/public/cpp/bindings/tests/associated_interface_unittest.cc b/mojo/public/cpp/bindings/tests/associated_interface_unittest.cc
index 625c49c73aa357ad33d18111ced2c96c37249555..be225e47610681b7df8197b87b14246c9f038bba 100644
--- a/mojo/public/cpp/bindings/tests/associated_interface_unittest.cc
+++ b/mojo/public/cpp/bindings/tests/associated_interface_unittest.cc
@@ -1178,6 +1178,12 @@ TEST_F(AssociatedInterfaceTest, CloseWithoutBindingAssociatedRequest) {
   run_loop.Run();
 }
 
+TEST_F(AssociatedInterfaceTest, GetIsolatedInterface) {
+  IntegerSenderAssociatedPtr sender;
+  GetIsolatedInterface(MakeRequest(&sender).PassHandle());
+  sender->Send(42);
+}
+
 }  // namespace
 }  // namespace test
 }  // namespace mojo