Add support for generating the QtCreator projects from GN.

tools/gn/import_manager.cc

 // 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.
 
 #include "tools/gn/import_manager.h"
 
 #include <memory>
 
 #include "base/stl_util.h"
 #include "tools/gn/parse_tree.h"
@@ skipping 73 matching lines @@
       }
     }
   }
 
   Scope::MergeOptions options;
   options.skip_private_vars = true;
   options.mark_dest_used = true;  // Don't require all imported values be used.
   return imported_scope->NonRecursiveMergeTo(scope, options, node_for_err,
                                              "import", err);
 }
+
+std::vector<SourceFile> ImportManager::GetImportedFiles() const {
+  std::vector<SourceFile> imported_files;
+  imported_files.resize(imports_.size());
+  std::transform(imports_.begin(), imports_.end(), imported_files.begin(),
+                 [](const ImportMap::value_type& val) { return val.first; });
+  return imported_files;
+}