Mojo: more idiomatic C++ bindings

mojo/services/dbus_echo/dbus_echo_service.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/at_exit.h"
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "mojo/common/channel_init.h"
 #include "mojo/dbus/dbus_external_service.h"
 #include "mojo/embedder/embedder.h"
 #include "mojo/public/cpp/environment/environment.h"
 #include "mojo/services/dbus_echo/echo.mojom.h"
 
 namespace {
 class EchoServiceImpl : public mojo::InterfaceImpl<mojo::EchoService> {
  public:
   EchoServiceImpl() {}
   virtual ~EchoServiceImpl() {}
 
   virtual void OnConnectionError() OVERRIDE {}
 
  protected:
   virtual void Echo(
-      const mojo::String& in_to_echo,
+      mojo::String in_to_echo,
       const mojo::Callback<void(mojo::String)>& callback) OVERRIDE {
-    DVLOG(1) << "Asked to echo " << in_to_echo.To<std::string>();
-    callback.Run(in_to_echo);
+    DVLOG(1) << "Asked to echo " << in_to_echo;
+    callback.Run(in_to_echo.Pass());
   }
 };
 
 const char kServiceName[] = "org.chromium.EchoService";
 }  // anonymous namespace
 
 int main(int argc, char** argv) {
   base::AtExitManager exit_manager;
   CommandLine::Init(argc, argv);
 
@@ skipping 10 matching lines @@
 
   base::MessageLoopForIO message_loop;
   base::RunLoop run_loop;
 
   mojo::DBusExternalService<EchoServiceImpl> echo_service(kServiceName);
   echo_service.Start();
 
   run_loop.Run();
   return 0;
 }