Port "Eclipse CDT settings" file generation from GYP to GN

tools/gn/eclipse_writer.h

Index: tools/gn/eclipse_writer.h
diff --git a/tools/gn/eclipse_writer.h b/tools/gn/eclipse_writer.h
new file mode 100644
index 0000000000000000000000000000000000000000..560b8729e02fc177aa265ef3639c0603207359fd
--- /dev/null
+++ b/tools/gn/eclipse_writer.h
@@ -0,0 +1,67 @@
+// Copyright 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_ECLIPSE_WRITER_H_
+#define TOOLS_GN_ECLIPSE_WRITER_H_
+
+#include <iosfwd>
+#include <map>
+#include <set>
+#include <string>
+#include <vector>
+
+#include "base/macros.h"
+
+class BuildSettings;
+class Builder;
+class Err;
+class Target;
+
+class EclipseWriter {
+ public:
+  static bool RunAndWriteFile(const BuildSettings* build_settings,
+                              const Builder* builder,
+                              Err* err);
+
+ private:
+  EclipseWriter(const BuildSettings* build_settings,
+                const Builder* builder,
+                std::ostream& out);
+  ~EclipseWriter();
+
+  void Run();
+
+  // Populates |include_dirs_| with the include dirs of all the targets for the
+  // default toolchain.
+  void GetAllIncludeDirs();
+
+  // Populates |defines_| with the defines of all the targets for the default
+  // toolchain.
+  void GetAllDefines();
+
+  // Returns true if |target| uses the default toolchain.
+  bool UsesDefaultToolchain(const Target* target) const;
+
+  // Writes the XML settings file.
+  void WriteCDTSettings();
+
+  const BuildSettings* build_settings_;
+  const Builder* builder_;
+
+  // The output stream for the settings file.
+  std::ostream& out_;
+
+  // Eclipse languages for which the include dirs and defines apply.
+  std::vector<std::string> languages_;
+
+  // The include dirs of all the targets which use the default toolchain.
+  std::set<std::string> include_dirs_;
+
+  // The defines of all the targets which use the default toolchain.
+  std::map<std::string, std::string> defines_;
+
+  DISALLOW_COPY_AND_ASSIGN(EclipseWriter);
+};
+
+#endif  // TOOLS_GN_ECLIPSE_WRITER_H_