Give the filter setup more context so it can figure out whether it's download...

net/base/filter.h

 // Copyright (c) 2006-2008 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.
 //
 // Filter performs filtering on data streams. Sample usage:
 //
 //   IStream* pre_filter_source;
 //   ...
 //   Filter* filter = Filter::Factory(filter_type, size);
 //   int pre_filter_data_len = filter->stream_buffer_size();
@@ skipping 47 matching lines @@
   // What URL was used to access this data?
   // Return false if gurl is not present.
   virtual bool GetURL(GURL* gurl) const = 0;
 
   // When was this data requested from a server?
   virtual base::Time GetRequestTime() const = 0;
 
   // Is data supplied from cache, or fresh across the net?
   virtual bool IsCachedContent() const = 0;
 
+  // Is this a download?
+  virtual bool IsDownload() const = 0;
+
   // Was this data flagged as a response to a request with an SDCH dictionary?
   virtual bool IsSdchResponse() const = 0;
 
   // How many bytes were read from the net or cache so far (and potentially
   // pushed into a filter for processing)?
   virtual int64 GetByteReadCount() const = 0;
 
   // What response code was received with the associated network transaction?
   // For example: 200 is ok.   4xx are error codes. etc.
   virtual int GetResponseCode() const = 0;
@@ skipping 160 matching lines @@
 
   // Context data from the owner of this filter.  Some filters need additional
   // context information (mime type, etc.) to properly function, and they access
   // this data via this reference member.
   const FilterContext& filter_context_;
 
   DISALLOW_COPY_AND_ASSIGN(Filter);
 };
 
 #endif  // NET_BASE_FILTER_H__