Update from https://crrev.com/306655

net/base/upload_bytes_element_reader.cc

 // Copyright (c) 2012 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 "net/base/upload_bytes_element_reader.h"
 
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
@@ skipping 30 matching lines @@
 
 bool UploadBytesElementReader::IsInMemory() const {
   return true;
 }
 
 int UploadBytesElementReader::Read(IOBuffer* buf,
                                    int buf_length,
                                    const CompletionCallback& callback) {
   DCHECK_LT(0, buf_length);
 
-  const size_t num_bytes_to_read =
-      std::min(BytesRemaining(), static_cast<uint64>(buf_length));
+  const int num_bytes_to_read = static_cast<int>(
+      std::min(BytesRemaining(), static_cast<uint64>(buf_length)));
 
   // Check if we have anything to copy first, because we are getting
   // the address of an element in |bytes_| and that will throw an
   // exception if |bytes_| is an empty vector.
   if (num_bytes_to_read > 0)
     memcpy(buf->data(), bytes_ + offset_, num_bytes_to_read);
 
   offset_ += num_bytes_to_read;
   return num_bytes_to_read;
 }
 
 
 UploadOwnedBytesElementReader::UploadOwnedBytesElementReader(
     std::vector<char>* data)
     : UploadBytesElementReader(vector_as_array(data), data->size()) {
   data_.swap(*data);
 }
 
 UploadOwnedBytesElementReader::~UploadOwnedBytesElementReader() {}
 
 UploadOwnedBytesElementReader*
 UploadOwnedBytesElementReader::CreateWithString(const std::string& string) {
   std::vector<char> data(string.begin(), string.end());
   return new UploadOwnedBytesElementReader(&data);
 }
 
 }  // namespace net