UploadDataStream now returns errors on failures

net/base/elements_upload_data_stream.cc

Index: net/base/elements_upload_data_stream.cc
diff --git a/net/base/elements_upload_data_stream.cc b/net/base/elements_upload_data_stream.cc
index bca7d4e7aab0ac1dc2b5d5c019100a8bdff23660..e1b6418439f2443334b7f474c5ed9ff948b0d027 100644
--- a/net/base/elements_upload_data_stream.cc
+++ b/net/base/elements_upload_data_stream.cc
@@ -20,7 +20,7 @@ ElementsUploadDataStream::ElementsUploadDataStream(
     : UploadDataStream(false, identifier),
       element_readers_(std::move(element_readers)),
       element_index_(0),
-      read_failed_(false),
+      read_failed_(OK),
       weak_ptr_factory_(this) {}
 
 ElementsUploadDataStream::~ElementsUploadDataStream() {
@@ -61,7 +61,7 @@ ElementsUploadDataStream::GetElementReaders() const {
 
 void ElementsUploadDataStream::ResetInternal() {
   weak_ptr_factory_.InvalidateWeakPtrs();
-  read_failed_ = false;
+  read_failed_ = OK;
   element_index_ = 0;
 }
 
@@ -125,16 +125,8 @@ int ElementsUploadDataStream::ReadElements(
     ProcessReadResult(buf, result);
   }
 
-  if (read_failed_) {
-    // If an error occured during read operation, then pad with zero.
-    // Otherwise the server will hang waiting for the rest of the data.
-    int num_bytes_to_fill =
-        static_cast<int>(std::min(static_cast<uint64_t>(buf->BytesRemaining()),
-                                  size() - position() - buf->BytesConsumed()));
-    DCHECK_GE(num_bytes_to_fill, 0);
-    memset(buf->data(), 0, num_bytes_to_fill);
-    buf->DidConsume(num_bytes_to_fill);
-  }
+  if (read_failed_ != OK)

[mmenke, 2016/06/21 21:13:13]

I'd suggest this instead:

if (buf->BytesConsumed() > 0)
  return buf->BytesConsumed();

return read_failed_;

That way, if we read bytes and have an error, we return the read bytes first. 
Probably doesn't matter, but seems safer.

[maksims (do not use this acc), 2016/06/22 15:10:32]

Done. It sitll has to check if there is now error, because it might fail on
another read round.

+    return read_failed_;
 
   return buf->BytesConsumed();
 }
@@ -158,7 +150,7 @@ void ElementsUploadDataStream::ProcessReadResult(
   if (result >= 0) {
     buf->DidConsume(result);
   } else {
-    read_failed_ = true;
+    read_failed_ = result;
   }
 }