Use filter context to track stats better in SDCH filtering

net/base/sdch_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.
 
 // SdchFilter applies open_vcdiff content decoding to a datastream.
 // This decoding uses a pre-cached dictionary of text fragments to decode
 // (expand) the stream back to its original contents.
 //
 // This SdchFilter internally uses open_vcdiff/vcdec library to do decoding.
 //
@@ skipping 66 matching lines @@
   std::string dictionary_hash_;
 
   // After assembling an entire dictionary hash (the first 9 bytes of the
   // sdch payload, we check to see if it is plausible, meaning it has a null
   // termination, and has 8 characters that are possible in a net-safe base64
   // encoding.  If the hash is not plausible, then the payload is probably not
   // an SDCH encoded bundle, and various error recovery strategies can be
   // attempted.
   bool dictionary_hash_is_plausible_;
 
-  // We hold an in-memory copy of the dictionary during the entire decoding.
-  // The char* data is embedded in a RefCounted dictionary_.
-  SdchManager::Dictionary* dictionary_;
+  // We hold an in-memory copy of the dictionary during the entire decoding, as
+  // it is used directly by the VC-DIFF decoding system.
+  // That char* data is part of the dictionary_ we hold a reference to.
+  scoped_refptr<SdchManager::Dictionary> dictionary_;
 
   // The decoder may demand a larger output buffer than the target of
   // ReadFilteredData so we buffer the excess output between calls.
   std::string dest_buffer_excess_;
   // To avoid moving strings around too much, we save the index into
   // dest_buffer_excess_ that has the next byte to output.
   size_t dest_buffer_excess_index_;
 
   // To get stats on activities, we keep track of source and target bytes.
   // Visit about:histograms/Sdch to see histogram data.
   size_t source_bytes_;
   size_t output_bytes_;
 
   // Record of chunk processing times for this filter.  Used only for stats
   // generations in histograms.
   std::vector<base::Time> read_times_;
 
   // Error recovery in content type may add an sdch filter type, in which case
   // we should gracefully perform pass through if the format is incorrect, or
   // an applicable dictionary can't be found.
   bool possible_pass_through_;
 
+  // The URL that is currently being filtered.
+  // This is used to restrict use of a dictionary to a specific URL or path.
+  GURL url_;
+
+  // To facilitate histogramming by individual filters, we store the connect
+  // time for the corresponding HTTP transaction, as well as whether this time
+  // was recalled from a cached entry.  The time is approximate, and may be
+  // bogus if the data was gotten from cache (i.e., it may be LOOOONG ago).
+  const base::Time connect_time_;
+  const bool was_cached_;
+
+  // To facilitate error recovery, allow filter to know if content is text/html
+  // by checking within this mime type (we may do a meta-refresh via html).
+  std::string mime_type_;
+
   DISALLOW_COPY_AND_ASSIGN(SdchFilter);
 };
 
 #endif  // NET_BASE_SDCH_FILTER_H_