Add support for reading .gypi files.

tools/gn/parse_tree.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_PARSE_TREE_H_
 #define TOOLS_GN_PARSE_TREE_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 98 matching lines @@
   void set_index(scoped_ptr<ParseNode> i) { index_ = i.Pass(); }
 
   // The member is the identifier on the right hand side of the dot. Will be
   // null if the index is set.
   const IdentifierNode* member() const { return member_.get(); }
   void set_member(scoped_ptr<IdentifierNode> i) { member_ = i.Pass(); }
 
  private:
   Value ExecuteArrayAccess(Scope* scope, Err* err) const;
   Value ExecuteScopeAccess(Scope* scope, Err* err) const;
+  // Takes a value known to be a dictionary.
+  Value ExecuteDictAccess(const Value* dict, Err* err) const;
 
   Token base_;
 
   // Either index or member will be set according to what type of access this
   // is.
   scoped_ptr<ParseNode> index_;
   scoped_ptr<IdentifierNode> member_;
 
   DISALLOW_COPY_AND_ASSIGN(AccessorNode);
 };
@@ skipping 259 matching lines @@
   }
 
  private:
   Token op_;
   scoped_ptr<ParseNode> operand_;
 
   DISALLOW_COPY_AND_ASSIGN(UnaryOpNode);
 };
 
 #endif  // TOOLS_GN_PARSE_TREE_H_