Add support for generating the QtCreator projects from GN.

tools/gn/qt_creator_writer.h

Index: tools/gn/qt_creator_writer.h
diff --git a/tools/gn/qt_creator_writer.h b/tools/gn/qt_creator_writer.h
new file mode 100644
index 0000000000000000000000000000000000000000..cea75fd18144e8296cb5d35d7f6c7d21f1879f0a
--- /dev/null
+++ b/tools/gn/qt_creator_writer.h
@@ -0,0 +1,56 @@
+// Copyright (c) 2016 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_QT_CREATOR_WRITER_H_
+#define TOOLS_GN_QT_CREATOR_WRITER_H_
+
+#include <set>
+#include <string>
+
+#include "base/files/file_path.h"
+#include "base/macros.h"
+#include "tools/gn/err.h"
+#include "tools/gn/target.h"
+
+class Builder;
+class BuildSettings;
+
+class QtCreatorWriter {
+ public:
+  static bool RunAndWriteFile(const BuildSettings* build_settings,
+                              const Builder* builder,
+                              Err* err,
+                              const std::string& root_target);
+
+ private:
+  QtCreatorWriter(const BuildSettings* build_settings,
+                  const Builder* builder,
+                  const base::FilePath& project_prefix,
+                  const std::string& root_target_name);
+  ~QtCreatorWriter();
+
+  void Run();
+
+  bool DiscoverTargets();
+  void HandleTarget(const Target* target);
+
+  void CollectDeps(const Target* target);
+  void AddToSources(const Target::FileList& files);
+  void GenerateFile(const base::FilePath::CharType* suffix,
+                    const std::set<std::string>& items);
+
+  const BuildSettings* build_settings_;
+  const Builder* builder_;
+  base::FilePath project_prefix_;
+  std::string root_target_name_;
+  std::set<const Target*> targets_;
+  std::set<std::string> sources_;
+  std::set<std::string> includes_;
+  std::set<std::string> defines_;
+  Err err_;
+
+  DISALLOW_COPY_AND_ASSIGN(QtCreatorWriter);
+};
+
+#endif  // TOOLS_GN_QT_CREATOR_WRITER_H_