[SPDY] Refactor SpdySession's write queue

net/spdy/spdy_frame_producer.h

+// Copyright (c) 2013 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_SPDY_SPDY_FRAME_PRODUCER_H_
+#define NET_SPDY_SPDY_FRAME_PRODUCER_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/base/net_export.h"
+
+namespace net {
+
+class SpdyFrame;
+
+// An object which provides a SpdyFrame for writing. We pass these
+// around instead of SpdyFrames since some frames have to be generated
+// "just in time".
+class NET_EXPORT_PRIVATE SpdyFrameProducer {
+ public:
+  SpdyFrameProducer();
+
+  // Produces the frame to be written. Will be called at most once.
+  virtual scoped_ptr<SpdyFrame> ProduceFrame() = 0;
+
+  virtual ~SpdyFrameProducer();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SpdyFrameProducer);
+};
+
+// A simple wrapper around a single SpdyFrame.
+class NET_EXPORT_PRIVATE SimpleFrameProducer : public SpdyFrameProducer {
+ public:
+  explicit SimpleFrameProducer(scoped_ptr<SpdyFrame> frame);
+
+  virtual ~SimpleFrameProducer();
+
+  virtual scoped_ptr<SpdyFrame> ProduceFrame() OVERRIDE;
+
+ private:
+  scoped_ptr<SpdyFrame> frame_;
+
+  DISALLOW_COPY_AND_ASSIGN(SimpleFrameProducer);
+};
+
+}  // namespace net
+
+#endif  // NET_SPDY_SPDY_FRAME_PRODUCER_H_