Add extra size check to avoid unwanted Seg Fault

headless/public/util/generic_url_request_job.cc

 // Copyright 2016 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 "headless/public/util/generic_url_request_job.h"
 
 #include <string.h>
 #include <algorithm>
 
 #include "base/logging.h"
@@ skipping 258 matching lines @@
 }
 
 std::string GenericURLRequestJob::GetPostData() const {
   if (!request_->has_upload())
     return "";
 
   const net::UploadDataStream* stream = request_->get_upload();
   if (!stream->GetElementReaders())
     return "";
 
+  if (stream->GetElementReaders()->size() == 0)
+    return "";
+
   DCHECK_EQ(1u, stream->GetElementReaders()->size());
   const net::UploadBytesElementReader* reader =
       (*stream->GetElementReaders())[0]->AsBytesReader();
   return std::string(reader->bytes(), reader->length());
 }
 
 const Request* GenericURLRequestJob::GetRequest() const {
   return this;
 }
 
@@ skipping 52 matching lines @@
   }
 
   mock_response_ = std::move(mock_response);
 
   OnFetchCompleteExtractHeaders(request_->url(),
                                 mock_response_->response_data.data(),
                                 mock_response_->response_data.size());
 }
 
 }  // namespace headless