Add support for reading blobs when using the network service.

content/network/net_adapters.h

-// Copyright 2017 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 CONTENT_NETWORK_NET_ADAPTERS_
-#define CONTENT_NETWORK_NET_ADAPTERS_
-
-#include <stdint.h>
-
-#include "base/macros.h"
-#include "mojo/public/cpp/system/data_pipe.h"
-#include "net/base/io_buffer.h"
-
-namespace content {
-
-// These adapters are used to transfer data between a Mojo pipe and the net
-// library.
-//
-//   Mojo pipe              Data flow    Network library
-//   ----------------------------------------------------------
-//   NetToMojoPendingBuffer    <---      NetToMojoIOBuffer
-//
-// While the operation is in progress, the Mojo-side objects keep ownership
-// of the Mojo pipe, which in turn is kept alive by the IOBuffer. This allows
-// the request to potentially outlive the object managing the translation.
-// Mojo side of a Net -> Mojo copy. The buffer is allocated by Mojo.
-class NetToMojoPendingBuffer
-    : public base::RefCountedThreadSafe<NetToMojoPendingBuffer> {
- public:
-  // Begins a two-phase write to the data pipe.
-  //
-  // On success, MOJO_RESULT_OK will be returned. The ownership of the given
-  // producer handle will be transferred to the new NetToMojoPendingBuffer that
-  // will be placed into *pending, and the size of the buffer will be in
-  // *num_bytes.
-  //
-  // On failure or MOJO_RESULT_SHOULD_WAIT, there will be no change to the
-  // handle, and *pending and *num_bytes will be unused.
-  static MojoResult BeginWrite(mojo::ScopedDataPipeProducerHandle* handle,
-                               scoped_refptr<NetToMojoPendingBuffer>* pending,
-                               uint32_t* num_bytes);
-  // Called to indicate the buffer is done being written to. Passes ownership
-  // of the pipe back to the caller.
-  mojo::ScopedDataPipeProducerHandle Complete(uint32_t num_bytes);
-  char* buffer() { return static_cast<char*>(buffer_); }
-
- private:
-  friend class base::RefCountedThreadSafe<NetToMojoPendingBuffer>;
-  // Takes ownership of the handle.
-  NetToMojoPendingBuffer(mojo::ScopedDataPipeProducerHandle handle,
-                         void* buffer);
-  ~NetToMojoPendingBuffer();
-  mojo::ScopedDataPipeProducerHandle handle_;
-  void* buffer_;
-  DISALLOW_COPY_AND_ASSIGN(NetToMojoPendingBuffer);
-};
-
-// Net side of a Net -> Mojo copy. The data will be read from the network and
-// copied into the buffer associated with the pending mojo write.
-class NetToMojoIOBuffer : public net::WrappedIOBuffer {
- public:
-  explicit NetToMojoIOBuffer(NetToMojoPendingBuffer* pending_buffer);
-
- private:
-  ~NetToMojoIOBuffer() override;
-  scoped_refptr<NetToMojoPendingBuffer> pending_buffer_;
-};
-
-}  // namespace content
-
-#endif  // CONTENT_NETWORK_NET_ADAPTERS_