Remove some InterfacePtr<> methods which directly deal with message pipe handles.

examples/surfaces_app/child_gl_impl.cc

Index: examples/surfaces_app/child_gl_impl.cc
diff --git a/examples/surfaces_app/child_gl_impl.cc b/examples/surfaces_app/child_gl_impl.cc
index 97cd9a13d2f02db62d4105aa908354dd0a7939bd..4463bf5ffc15d264c7420efd5387f3bd3a19f854 100644
--- a/examples/surfaces_app/child_gl_impl.cc
+++ b/examples/surfaces_app/child_gl_impl.cc
@@ -59,11 +59,9 @@ ChildGLImpl::ChildGLImpl(ApplicationConnection* surfaces_service_connection,
   ResourceReturnerPtr returner_ptr;
   returner_binding_.Bind(GetProxy(&returner_ptr));
   surface_->SetResourceReturner(returner_ptr.Pass());
-  context_ =
-      MojoGLES2CreateContext(command_buffer.PassMessagePipe().release().value(),
-                             &ContextLostThunk,
-                             this,
-                             Environment::GetDefaultAsyncWaiter());
+  context_ = MojoGLES2CreateContext(
+      command_buffer.PassInterface().PassHandle().release().value(),
+      &ContextLostThunk, this, Environment::GetDefaultAsyncWaiter());
   DCHECK(context_);
   MojoGLES2MakeCurrent(context_);
 }