IndexedDB: Fixed support for empty blobs.

net/base/upload_data_stream.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_data_stream.h"
 
 #include "base/callback_helpers.h"
 #include "base/logging.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
@@ skipping 25 matching lines @@
     OnInitCompleted(result);
   }
   return result;
 }
 
 int UploadDataStream::Read(IOBuffer* buf,
                            int buf_len,
                            const CompletionCallback& callback) {
   DCHECK(!callback.is_null() || IsInMemory());
   DCHECK(initialized_successfully_);
-  DCHECK_GT(buf_len, 0);
-  if (is_eof_)
+  DCHECK_GE(buf_len, 0);
+  if (!buf_len || is_eof_)

[michaeln, 2015/03/09 21:15:18]

This is a little troublesome because generally reading 0 bytes back indicates
eof. How is this hit by the tests?

[mmenke, 2015/03/09 21:20:09]

Can we instead set is_eof_ to true in SetSize, if size is 0?  And have a net/
test for that case, as we apparently don't have one currently.

In fact, this fix and that change should be in a separate CL.  I'm happy to
review it.

[mmenke, 2015/03/09 21:22:41]

The test should be in elements_upload_data_stream_unittest.cc (We don't
currently test this class independently, though we probably should).

[cmumford, 2015/03/09 22:05:11]

Reverted this change as suggested.

     return 0;
   int result = ReadInternal(buf, buf_len);
   if (result == ERR_IO_PENDING) {
     DCHECK(!IsInMemory());
     callback_ = callback;
   } else {
     OnReadCompleted(result);
   }
   return result;
 }
@@ skipping 61 matching lines @@
       is_eof_ = true;
   }
 
   DCHECK(result > 0 || is_eof_);
 
   if (!callback_.is_null())
     base::ResetAndReturn(&callback_).Run(result);
 }
 
 }  // namespace net