Remove implicit conversions from scoped_refptr to T* in ppapi/

ppapi/proxy/platform_verification_private_resource.cc

 // Copyright 2013 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 "ppapi/proxy/platform_verification_private_resource.h"
 
 #include "base/bind.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/proxy/dispatch_reply_message.h"
 #include "ppapi/proxy/ppapi_messages.h"
@@ skipping 34 matching lines @@
       VarTracker::IsVarTypeRefcounted(platform_key_certificate->type)) {
     return PP_ERROR_BADARGUMENT;
   }
 
   StringVar* service_id_str = StringVar::FromPPVar(service_id);
   if (!service_id_str)
     return PP_ERROR_BADARGUMENT;
 
   scoped_refptr<ArrayBufferVar> challenge_buffer =
       ArrayBufferVar::FromPPVar(challenge);
-  if (!challenge_buffer)
+  if (!challenge_buffer.get())
     return PP_ERROR_BADARGUMENT;
 
   uint8_t* challenge_data = static_cast<uint8_t*>(challenge_buffer->Map());
   uint32 challenge_length = challenge_buffer->ByteLength();
   std::vector<uint8_t> challenge_vector(challenge_data,
                                         challenge_data + challenge_length);
   challenge_buffer->Unmap();
 
   PpapiHostMsg_PlatformVerification_ChallengePlatform challenge_message(
       service_id_str->value(), challenge_vector);
@@ skipping 28 matching lines @@
             raw_signed_data_signature.size(),
             &raw_signed_data_signature.front()))->GetPPVar();
     *(output_params.platform_key_certificate) =
         (new StringVar(raw_platform_key_certificate))->GetPPVar();
   }
   output_params.callback->Run(params.result());
 }
 
 }  // namespace proxy
 }  // namespace ppapi