Update from https://crrev.com/306655

net/base/upload_file_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_file_element_reader.h"
 
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/location.h"
 #include "base/profiler/scoped_tracker.h"
@@ skipping 60 matching lines @@
 
 uint64 UploadFileElementReader::BytesRemaining() const {
   return bytes_remaining_;
 }
 
 int UploadFileElementReader::Read(IOBuffer* buf,
                                   int buf_length,
                                   const CompletionCallback& callback) {
   DCHECK(!callback.is_null());
 
-  uint64 num_bytes_to_read =
-      std::min(BytesRemaining(), static_cast<uint64>(buf_length));
+  int num_bytes_to_read = static_cast<int>(
+      std::min(BytesRemaining(), static_cast<uint64>(buf_length)));
   if (num_bytes_to_read == 0)
     return 0;
 
   int result = file_stream_->Read(
       buf, num_bytes_to_read,
       base::Bind(base::IgnoreResult(&UploadFileElementReader::OnReadCompleted),
                  weak_ptr_factory_.GetWeakPtr(),
                  callback));
   // Even in async mode, FileStream::Read() may return the result synchronously.
   if (result != ERR_IO_PENDING)
@@ skipping 40 matching lines @@
 }
 
 void UploadFileElementReader::OnSeekCompleted(
     const CompletionCallback& callback,
     int64 result) {
   DCHECK(!callback.is_null());
 
   if (result < 0) {
     DLOG(WARNING) << "Failed to seek \"" << path_.value()
                   << "\" to offset: " << range_offset_ << " (" << result << ")";
-    callback.Run(result);
+    callback.Run(static_cast<int>(result));
     return;
   }
 
   base::File::Info* file_info = new base::File::Info;
   bool posted = base::PostTaskAndReplyWithResult(
       task_runner_.get(),
       FROM_HERE,
       base::Bind(&base::GetFileInfo, path_, file_info),
       base::Bind(&UploadFileElementReader::OnGetFileInfoCompleted,
                  weak_ptr_factory_.GetWeakPtr(),
@@ skipping 55 matching lines @@
 ScopedOverridingContentLengthForTests(uint64 value) {
   overriding_content_length = value;
 }
 
 UploadFileElementReader::ScopedOverridingContentLengthForTests::
 ~ScopedOverridingContentLengthForTests() {
   overriding_content_length = 0;
 }
 
 }  // namespace net