UploadDataStream now returns errors on failures

net/base/upload_data_stream.h

 // 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.
 
 #ifndef NET_BASE_UPLOAD_DATA_STREAM_H_
 #define NET_BASE_UPLOAD_DATA_STREAM_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 38 matching lines @@
   // data stream to |buf| and returns the number of bytes read; otherwise,
   // returns ERR_IO_PENDING and calls |callback| with the number of bytes read.
   // Partial reads are allowed. Zero is returned on a call to Read when there
   // are no remaining bytes in the stream, and IsEof() will return true
   // hereafter.
   //
   // If there's less data to read than we initially observed (i.e. the actual
   // upload data is smaller than size()), zeros are padded to ensure that
   // size() bytes can be read, which can happen for TYPE_FILE payloads.
   //
-  // Reads are currently not allowed to fail - they must either return
-  // a value >= 0 or ERR_IO_PENDING, and call OnReadCompleted with a
-  // value >= 0.
+  // Reads can fail - they can either return
+  // ERR_FAILED or ERR_IO_PENDING on failures, and must call OnReadCompleted
+  // with an error value.

[mmenke, 2016/06/06 16:22:33]

Think this should separate ERR_FAILED with ERR_IO_PENDING (They can also return
ERR_IO_PENDING on success).  Maybe just remove this paragraph, and modify the
first one to mention the failure case.  i.e., something like:


When possible, reads up to |buf_len| bytes synchronously from the upload
data stream to |buf| and returns the number of bytes read. Returns a network
error on synchronous failure. Returns ERR_IO_PENDING and calls |callback|
with the number of bytes read or error code on asynchronous completion.
Partial reads are allowed....

[maksims (do not use this acc), 2016/06/21 11:09:25]

Should I remove your TODO now?

   // TODO(mmenke):  Investigate letting reads fail.
   int Read(IOBuffer* buf, int buf_len, const CompletionCallback& callback);
 
   // Returns the total size of the data stream and the current position.
   // When the data is chunked, always returns zero. Must always return the same
   // value after each call to Initialize().
   uint64_t size() const { return total_size_; }
   uint64_t position() const { return current_position_; }
 
   // See constructor for description.
@@ skipping 65 matching lines @@
   bool is_eof_;
 
   CompletionCallback callback_;
 
   DISALLOW_COPY_AND_ASSIGN(UploadDataStream);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_UPLOAD_DATA_STREAM_H_