tools/gn: Add out-of-line copy ctors for complex classes.

tools/gn/token.h

 // Copyright (c) 2013 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.
 
 #ifndef TOOLS_GN_TOKEN_H_
 #define TOOLS_GN_TOKEN_H_
 
 #include "base/strings/string_piece.h"
 #include "tools/gn/location.h"
 
@@ skipping 40 matching lines @@
     SUFFIX_COMMENT,    // #...\n on a line following other code.
     BLOCK_COMMENT,     // #...\n line comment, but free-standing.
 
     UNCLASSIFIED_OPERATOR,
 
     NUM_TYPES
   };
 
   Token();
   Token(const Location& location, Type t, const base::StringPiece& v);
+  Token(const Token& other);
 
   Type type() const { return type_; }
   const base::StringPiece& value() const { return value_; }
   const Location& location() const { return location_; }
   void set_location(Location location) { location_ = location; }
   LocationRange range() const {
     return LocationRange(
         location_,
         Location(location_.file(),
                  location_.line_number(),
                  location_.column_number() + static_cast<int>(value_.size()),
                  location_.byte() + static_cast<int>(value_.size())));
   }
 
   // Helper functions for comparing this token to something.
   bool IsIdentifierEqualTo(const char* v) const;
   bool IsStringEqualTo(const char* v) const;
 
  private:
   Type type_;
   base::StringPiece value_;
   Location location_;
 };
 
 #endif  // TOOLS_GN_TOKEN_H_