Added brotli enc/ and tools/ directories.

third_party/brotli/enc/utf8_util.h

+/* Copyright 2013 Google Inc. All Rights Reserved.
+
+   Distributed under MIT license.
+   See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+// Heuristics for deciding about the UTF8-ness of strings.
+
+#ifndef BROTLI_ENC_UTF8_UTIL_H_
+#define BROTLI_ENC_UTF8_UTIL_H_
+
+#include "./types.h"
+
+namespace brotli {
+
+static const double kMinUTF8Ratio = 0.75;
+
+// Returns true if at least min_fraction of the bytes between pos and
+// pos + length in the (data, mask) ringbuffer is UTF8-encoded.
+bool IsMostlyUTF8(const uint8_t* data, const size_t pos, const size_t mask,
+                  const size_t length, const double min_fraction);
+
+}  // namespace brotli
+
+#endif  // BROTLI_ENC_UTF8_UTIL_H_