[ON HOLD] Implement pull-based design for content decoding

net/filter/stream_source_util.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 NET_FILTER_STREAM_SOURCE_UTIL_H
+#define NET_FILTER_STREAM_SOURCE_UTIL_H
+
+#include <memory>
+#include <vector>
+
+#include "net/filter/stream_source.h"
+
+namespace net {
+
+class HttpResponseHeaders;
+
+class StreamSourceUtil {
+ public:
+  // This method constructs a chain of StreamSources from a vector of
+  // Content-Type values and an SdchStreamSourceDelegate. If any of the
+  // constructed StreamSources are SdchStreamSources, they will be constructed
+  // with |delegate|.

[Randy Smith (Not in Mondays), 2016/04/26 21:54:02]

?  There is no |delegate| in the argument list (and since it's static, that
means it's not there).

[xunjieli, 2016/07/20 21:00:48]

Done.

+  static std::unique_ptr<StreamSource> BuildSourceChain(
+      std::unique_ptr<StreamSource> previous,
+      HttpResponseHeaders* headers);

[Randy Smith (Not in Mondays), 2016/04/26 21:54:01]

I have some urge to pull this functionality up into URLRequestHttpJob; it's
pretty HTTP specific, so it doesn't strike me as out of place there, and I think
it likely that with that and a few other tweaks we can break the circular
dependency of StreamSource -> all different types of StreamSources ->
StreamSource.  But it's only vaguely related to this CL, so feel free to look
into doing it or not as you choose.

[xunjieli, 2016/07/20 21:00:48]

Done.

+
+  // Converts a StreamSource::SourceType to its string representation.
+  static std::string SourceTypeAsString(StreamSource::SourceType type);

[Randy Smith (Not in Mondays), 2016/04/26 21:54:02]

I suspect (haven't traced through the code) that this functionality could be
replaced by a virtual function on StreamSource, which would again be a nice
dependency breakage.

[xunjieli, 2016/07/20 21:00:48]

Done.

+
+  // Returns a string that represents the filter chain that starts at and
+  // includes |source|.
+  static std::string OrderedStreamSourceList(StreamSource* source);

[Randy Smith (Not in Mondays), 2016/04/26 21:54:02]

And similarly, I'd recommend having a virtual method on StreamSource that
returns a string describing the stream, and a non-virtual method on StreamSource
that concatenates the result of that methods with the result of calling itself
on previous_.

[xunjieli, 2016/07/20 21:00:48]

Done.

+};
+
+}  // namespace net
+
+#endif  // NET_FILTER_STREAM_SOURCE_UTIL_H