Cleanup remaining class/struct fwd declarations

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>
 #include <utility>
 
 #include "base/containers/hash_tables.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_vector.h"
 #include "tools/gn/err.h"
 #include "tools/gn/pattern.h"
 #include "tools/gn/source_dir.h"
 #include "tools/gn/value.h"
 
-class FunctionCallNode;
-class ImportManager;
 class Item;
 class ParseNode;
 class Settings;
-class TargetManager;
 class Template;
 
 // Scope for the script execution.
 //
 // Scopes are nested. Writing goes into the toplevel scope, reading checks
 // values resursively down the stack until a match is found or there are no
 // more containing scopes.
 //
 // A containing scope can be const or non-const. The const containing scope is
 // used primarily to refer to the master build config which is shared across
@@ skipping 340 matching lines @@
 
   typedef std::set<ProgrammaticProvider*> ProviderSet;
   ProviderSet programmatic_providers_;
 
   SourceDir source_dir_;
 
   DISALLOW_COPY_AND_ASSIGN(Scope);
 };
 
 #endif  // TOOLS_GN_SCOPE_H_