If SDCH is disabled, don't add an SDCH filter

net/filter/filter.cc

 // Copyright 2014 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.
 
 #include "net/filter/filter.h"
 
 #include "base/files/file_path.h"
 #include "base/strings/string_util.h"
 #include "net/base/io_buffer.h"
 #include "net/base/mime_util.h"
@@ skipping 351 matching lines @@
                                  Filter* filter_list) {
   scoped_ptr<Filter> first_filter;  // Soon to be start of chain.
   switch (type_id) {
     case FILTER_TYPE_GZIP_HELPING_SDCH:
     case FILTER_TYPE_DEFLATE:
     case FILTER_TYPE_GZIP:
       first_filter.reset(InitGZipFilter(type_id, buffer_size));
       break;
     case FILTER_TYPE_SDCH:
     case FILTER_TYPE_SDCH_POSSIBLE:
-      first_filter.reset(InitSdchFilter(type_id, filter_context, buffer_size));
+      if (SdchManager::Global() && SdchManager::sdch_enabled()) {
+        first_filter.reset(
+            InitSdchFilter(type_id, filter_context, buffer_size));
+      }
       break;
     default:
       break;
   }
 
   if (!first_filter.get())
     return NULL;
 
   first_filter->next_filter_.reset(filter_list);
   return first_filter.release();
 }
 
 void Filter::InitBuffer(int buffer_size) {
   DCHECK(!stream_buffer());
   DCHECK_GT(buffer_size, 0);
   stream_buffer_ = new IOBuffer(buffer_size);
   stream_buffer_size_ = buffer_size;
 }
 
 void Filter::PushDataIntoNextFilter() {
   IOBuffer* next_buffer = next_filter_->stream_buffer();
   int next_size = next_filter_->stream_buffer_size();
   last_status_ = ReadFilteredData(next_buffer->data(), &next_size);
   if (FILTER_ERROR != last_status_)
     next_filter_->FlushStreamBuffer(next_size);
 }
 
 }  // namespace net