components: Add out-of-line copy ctors for complex classes.

components/query_parser/snippet.h

 // 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.
 
 // This module computes snippets of queries based on hits in the documents
 // for display in history search results.
 
 #ifndef COMPONENTS_QUERY_PARSER_SNIPPET_H__
 #define COMPONENTS_QUERY_PARSER_SNIPPET_H__
 
@@ skipping 29 matching lines @@
                                     const std::string& column_num,
                                     MatchPositions* match_positions);
 
   // Converts match positions as returned from ExtractMatchPositions to be in
   // terms of a UTF-16 2-byte code unit.
   static void ConvertMatchPositionsToWide(
       const std::string& utf8_string,
       Snippet::MatchPositions* match_positions);
 
   Snippet();
+  Snippet(const Snippet& other);
   ~Snippet();
 
   // Given |matches|, the match positions within |document|, compute the snippet
   // for the document.
   // Note that |document| is UTF-8 and the offsets in |matches| are byte
   // offsets.
   void ComputeSnippet(const MatchPositions& matches,
                       const std::string& document);
 
   const base::string16& text() const { return text_; }
   const MatchPositions& matches() const { return matches_; }
 
   // Efficiently swaps the contents of this snippet with the other.
   void Swap(Snippet* other);
 
  private:
   // The text of the snippet.
   base::string16 text_;
 
   // The matches within text_.
   MatchPositions matches_;
 };
 
 }  // namespace query_parser
 
 #endif  // COMPONENTS_QUERY_PARSER_SNIPPET_H__