Add net::BrotliSourceStream

net/filter/brotli_source_stream_disabled.cc

Index: net/filter/brotli_source_stream_disabled.cc
diff --git a/net/filter/source_stream.cc b/net/filter/brotli_source_stream_disabled.cc
similarity index 51%
copy from net/filter/source_stream.cc
copy to net/filter/brotli_source_stream_disabled.cc
index e2c4e6e2539fddfe2a54c19ce35fa39be5b9db4f..986397cb94e44af761f41050e15c116b64f84694 100644
--- a/net/filter/source_stream.cc
+++ b/net/filter/brotli_source_stream_disabled.cc
@@ -2,16 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "net/filter/source_stream.h"
+#include "net/filter/brotli_source_stream.h"
 
 namespace net {
 
-SourceStream::SourceStream(SourceType type) : type_(type) {}
-
-SourceStream::~SourceStream() {}
-
-std::string SourceStream::Description() const {
-  return "";
+std::unique_ptr<FilterSourceStream> CreateBrotliSourceStream(
+    std::unique_ptr<SourceStream> previous) {
+  return nullptr;
 }
 
 }  // namespace net