GN: Use std::unique_ptr for owning pointers in Scope::NamedScopeMap.

tools/gn/scope.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_SCOPE_H_
 #define TOOLS_GN_SCOPE_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 315 matching lines @@
   const Settings* settings_;
 
   // Bits set for different modes. See the flag definitions in the .cc file
   // for more.
   unsigned mode_flags_;
 
   typedef base::hash_map<base::StringPiece, Record, base::StringPieceHash>
       RecordMap;
   RecordMap values_;
 
-  // Owning pointers. Note that this can't use string pieces since the names
-  // are constructed from Values which might be deallocated before this goes
-  // out of scope.
-  typedef base::hash_map<std::string, Scope*> NamedScopeMap;
+  // Note that this can't use string pieces since the names are constructed from
+  // Values which might be deallocated before this goes out of scope.
+  typedef base::hash_map<std::string, std::unique_ptr<Scope>> NamedScopeMap;
   NamedScopeMap target_defaults_;
 
   // Null indicates not set and that we should fallback to the containing
   // scope's filter.
   std::unique_ptr<PatternList> sources_assignment_filter_;
 
   // Owning pointers, must be deleted.
   typedef std::map<std::string, scoped_refptr<const Template> > TemplateMap;
   TemplateMap templates_;
 
   ItemVector* item_collector_;
 
   // Opaque pointers. See SetProperty() above.
   typedef std::map<const void*, void*> PropertyMap;
   PropertyMap properties_;
 
   typedef std::set<ProgrammaticProvider*> ProviderSet;
   ProviderSet programmatic_providers_;
 
   SourceDir source_dir_;
 
   DISALLOW_COPY_AND_ASSIGN(Scope);
 };
 
 #endif  // TOOLS_GN_SCOPE_H_