Blimp: Add BlobChannelSender implementation

blimp/net/blob_channel/blob_channel_bindings.h

+// Copyright 2016 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 BLIMP_NET_BLOB_CHANNEL_BLOB_CHANNEL_BINDINGS_H_
+#define BLIMP_NET_BLOB_CHANNEL_BLOB_CHANNEL_BINDINGS_H_
+
+#include <string>
+#include <vector>
+
+namespace blimp {
+
+// Interfaces for attaching transport-specific implementations to BlobChannel
+// operations. The caller is responsible for handling call deduplication;
+// bindings objects simply execute the command.
+
+class BlobSenderBindings {

[Wez, 2016/04/15 17:15:16]

This just looks like a BlobSender "delegate"; why "Bindings"?

[Kevin M, 2016/04/15 22:42:56]

It is just a delegate. So, now it's a Delegate. :)

Done.

+ public:
+  // Send blob |id| with payload |data| to the receiver.
+  virtual void Send(const std::string& id,
+                    const std::vector<uint8_t>& data) = 0;

[Wez, 2016/04/15 17:15:16]

Provide typedefs for these so that BlobChannel/BlobCache code can use BlobId and
BlobData/BlobContent/BlobBytes for better readability.

Why use vector<uint8_t> rather than string? Isn't a string effectively just a
vector<char> and so equivalent for our purposes?

This interface seems very expensive; if the sender wants to "trickle" the blobs
across to the receiver, for instance, then it has to accept a complete copy of
the blob payload and store it internally, despite the cache itself already
having a copy.

If we add an explicit concept of a ref-counted read-only Blob then we can avoid
unnecessary copying.

[Kevin M, 2016/04/15 22:42:56]

Added "types.h" for standardization.

+};
+
+}  // namespace blimp
+
+#endif  // BLIMP_NET_BLOB_CHANNEL_BLOB_CHANNEL_BINDINGS_H_