Add 'third_party/abseil_cpp/' from commit '768eb2ca28'

git-subtree-dir: third_party/abseil_cpp
git-subtree-mainline: ffb2ae54be
git-subtree-split: 768eb2ca28

third_party/abseil_cpp/absl/random/seed_sequences.cc

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+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "absl/random/seed_sequences.h"
+
+#include "absl/random/internal/pool_urbg.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+SeedSeq MakeSeedSeq() {
+  SeedSeq::result_type seed_material[8];
+  random_internal::RandenPool<uint32_t>::Fill(absl::MakeSpan(seed_material));
+  return SeedSeq(std::begin(seed_material), std::end(seed_material));
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl