Add a UniqueVector class to GN

tools/gn/output_file.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_OUTPUT_FILE_H_
 #define TOOLS_GN_OUTPUT_FILE_H_
 
 #include <string>
 
+#include "base/containers/hash_tables.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/source_file.h"
 
 // A simple wrapper around a string that indicates the string is a path
 // relative to the output directory.
 class OutputFile {
  public:
   OutputFile() : value_() {}
   explicit OutputFile(const base::StringPiece& str)
       : value_(str.data(), str.size()) {
@@ skipping 14 matching lines @@
     return value_ != other.value_;
   }
   bool operator<(const OutputFile& other) const {
     return value_ < other.value_;
   }
 
  private:
   std::string value_;
 };
 
+namespace BASE_HASH_NAMESPACE {
+
+#if defined(COMPILER_GCC)
+template<> struct hash<OutputFile> {
+  std::size_t operator()(const OutputFile& v) const {
+    hash<std::string> h;
+    return h(v.value());
+  }
+};
+#elif defined(COMPILER_MSVC)
+inline size_t hash_value(const OutputFile& v) {
+  return hash_value(v.value());
+}
+#endif  // COMPILER...
+
+}  // namespace BASE_HASH_NAMESPACE
+
+inline void swap(OutputFile& lhs, OutputFile& rhs) {
+  lhs.value().swap(rhs.value());
+}
+
 #endif  // TOOLS_GN_OUTPUT_FILE_H_