Don't use a scoped_refptr for StringVar::FromPPVar

ppapi/proxy/ppp_messaging_proxy_test.cc

 // Copyright (c) 2011 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 <cstring>
 
 #include "base/synchronization/waitable_event.h"
 #include "ppapi/c/pp_var.h"
 #include "ppapi/c/ppb_var.h"
 #include "ppapi/c/ppp_messaging.h"
@@ skipping 110 matching lines @@
   EXPECT_EQ(expected_var.value.as_double, received_var.value.as_double);
 
   expected_var.type = PP_VARTYPE_STRING;
   expected_var.value.as_id = 1979;
   ResetReceived();
   ppp_messaging->HandleMessage(expected_instance, expected_var);
   handle_message_called.Wait();
   EXPECT_EQ(expected_instance, received_instance);
   EXPECT_EQ(expected_var.type, received_var.type);
 
-  scoped_refptr<StringVar> received_string(StringVar::FromPPVar(received_var));
+  StringVar* received_string = StringVar::FromPPVar(received_var);
   ASSERT_TRUE(received_string.get());
   EXPECT_EQ(kTestString, received_string->value());
   // Now release the var, and the string should go away (because the ref
   // count should be one).
   plugin().var_tracker().ReleaseVar(received_var);
   EXPECT_FALSE(StringVar::FromPPVar(received_var).get());
 }
 
 }  // namespace proxy
 }  // namespace ppapi