Fix UnindexedRulesetWriter finishing.

components/subresource_filter/core/common/unindexed_ruleset.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.
 
 // Semantically speaking, an unindexed ruleset consists of a single
 // proto::FilteringRules message. However, because the ruleset can be relatively
 // large, we want to avoid deserializing all of it at once, as doing so can lead
 // to memory allocation bursts.
 //
 // To work around the limitation that partial (or streaming) deserialization is
@@ skipping 24 matching lines @@
   // Note: The |stream| should outlive |this| instance.
   explicit UnindexedRulesetReader(
       google::protobuf::io::ZeroCopyInputStream* stream);
   ~UnindexedRulesetReader();
 
   // Reads the next ruleset |chunk| from the |input|. Returns false iff reached
   // the end of the stream or an error occurred. Once returned false, calling
   // ReadNextChunk is undefined befaviour.
   bool ReadNextChunk(proto::FilteringRules* chunk);
 
+  // Returns how many bytes of the |stream| have been consumed.
+  int num_bytes_read() const { return coded_stream_.CurrentPosition(); }
+
  private:
   google::protobuf::io::CodedInputStream coded_stream_;
 
   DISALLOW_COPY_AND_ASSIGN(UnindexedRulesetReader);
 };
 
 // Divides an unindexed ruleset into chunks and writes them into |stream|.
 //
 // Writing methods of this class return bool false if an I/O error occurrs
 // during these calls. In this case the UnindexedRulesetWriter becomes broken,
@@ skipping 33 matching lines @@
 
   const int max_rules_per_chunk_ = 0;
   proto::FilteringRules pending_chunk_;
 
   DISALLOW_COPY_AND_ASSIGN(UnindexedRulesetWriter);
 };
 
 }  // namespace subresource_filter
 
 #endif  // COMPONENTS_SUBRESOURCE_FILTER_CORE_COMMON_UNINDEXED_RULESET_H_