Add a fuzzer for SfntlyWrapper::SubsetFont().

third_party/sfntly/BUILD.gn

 # Copyright 2014 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.
 
+import("//testing/libfuzzer/fuzzer_test.gni")
+
 declare_args() {
   # Flip to true to build sfntly sample programs.
   build_sfntly_samples = false
 }
 
 config("sfntly_common_config") {
   defines = [ "SFNTLY_NO_EXCEPTION" ]
   include_dirs = [ "src/cpp/src" ]
 }
 
@@ skipping 136 matching lines @@
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
 
   configs += [ ":sfntly_common_config" ]
   deps = [
     ":sfntly_chromium",
     "//third_party/icu:icuuc",
   ]
 }
 
+fuzzer_test("sfntly_fuzzer") {
+  sources = [
+    "fuzzers/subset_font_fuzzer.cc",
+  ]
+  deps = [
+    ":sfntly",
+    "//base/test:test_support",
+  ]
+  seed_corpus = "fuzzers/corpora/sfntly_fuzzer"
+}
+
 if (build_sfntly_samples) {
   source_set("sfntly_subtly") {
     sources = [
       "src/cpp/src/sample/subtly/character_predicate.cc",
       "src/cpp/src/sample/subtly/character_predicate.h",
       "src/cpp/src/sample/subtly/font_assembler.cc",
       "src/cpp/src/sample/subtly/font_assembler.h",
       "src/cpp/src/sample/subtly/font_info.cc",
       "src/cpp/src/sample/subtly/font_info.h",
       "src/cpp/src/sample/subtly/merger.cc",
@@ skipping 87 matching lines @@
     configs += [ ":sfntly_common_config" ]
     deps = [
       ":sfntly",
       ":sfntly_subtly",
     ]
     include_dirs = [ "src/cpp/src/sample" ]
   }
 
   # TODO(thestig): Get sfntly_unittests to build.
 }