Added brotli enc/ and tools/ directories.

third_party/brotli/BUILD.gn

Index: third_party/brotli/BUILD.gn
diff --git a/third_party/brotli/BUILD.gn b/third_party/brotli/BUILD.gn
index e25cf2b45c078ac558e538bef3160c144d237696..5b13e6f3b7aba702f7794fc274f48d72dd52e63e 100644
--- a/third_party/brotli/BUILD.gn
+++ b/third_party/brotli/BUILD.gn
@@ -30,3 +30,70 @@ source_set("brotli") {
 
   include_dirs = [ "dec" ]
 }
+
+if (current_toolchain == host_toolchain) {
+  executable("bro") {
+    sources = [
+      "enc/backward_references.cc",
+      "enc/backward_references.h",
+      "enc/bit_cost.h",
+      "enc/block_splitter.cc",
+      "enc/block_splitter.h",
+      "enc/brotli_bit_stream.cc",
+      "enc/brotli_bit_stream.h",
+      "enc/cluster.h",
+      "enc/command.h",
+      "enc/compress_fragment.cc",
+      "enc/compress_fragment.h",
+      "enc/compress_fragment_two_pass.cc",
+      "enc/compress_fragment_two_pass.h",
+      "enc/compressor.h",
+      "enc/context.h",
+      "enc/dictionary_hash.h",
+      "enc/encode.cc",
+      "enc/encode.h",
+      "enc/encode_parallel.cc",
+      "enc/encode_parallel.h",
+      "enc/entropy_encode.cc",
+      "enc/entropy_encode.h",
+      "enc/entropy_encode_static.h",
+      "enc/fast_log.h",
+      "enc/find_match_length.h",
+      "enc/hash.h ",
+      "enc/histogram.cc",
+      "enc/histogram.h",
+      "enc/literal_cost.cc",
+      "enc/literal_cost.h",
+      "enc/metablock.cc",
+      "enc/metablock.h",
+      "enc/port.h ",
+      "enc/prefix.h",
+      "enc/ringbuffer.h",
+      "enc/static_dict.cc",
+      "enc/static_dict.h",
+      "enc/static_dict_lut.h",
+      "enc/streams.cc",
+      "enc/streams.h",
+      "enc/transform.h",
+      "enc/types.h",
+      "enc/utf8_util.cc",
+      "enc/utf8_util.h",
+      "enc/write_bits.h",
+      "tools/bro.cc",
+    ]
+    deps = [
+      ":brotli",
+    ]
+
+    # Always build release since this is a build tool.
+    if (is_debug) {
+      configs -= [ "//build/config:debug" ]
+      configs += [ "//build/config:release" ]
+    }
+    if (is_posix) {
+      configs -= [ "//build/config/gcc:no_exceptions" ]
+    } else if (is_win) {
+      cflags_cc = [ "/EHsc" ]
+    }
+  }
+}