Add fuzzer for (A)PNG decoder

third_party/WebKit/Source/platform/BUILD.gn

Index: third_party/WebKit/Source/platform/BUILD.gn
diff --git a/third_party/WebKit/Source/platform/BUILD.gn b/third_party/WebKit/Source/platform/BUILD.gn
index d45fa60f61b735f57de7498d307ca52ad149ee75..2b5f6872a291e7dd3396462c2cfa7e8916d8eef9 100644
--- a/third_party/WebKit/Source/platform/BUILD.gn
+++ b/third_party/WebKit/Source/platform/BUILD.gn
@@ -2020,6 +2020,19 @@ fuzzer_test("web_icon_sizes_fuzzer") {
   dict = "//testing/libfuzzer/fuzzers/dicts/web_icon_sizes.dict"
 }
 
+fuzzer_test("blink_png_decoder_fuzzer") {
+  sources = [
+    "PngFuzzer.cpp",
+  ]
+  deps = [
+    ":blink_fuzzer_test_support",
+    ":platform",
+    "//third_party/libpng",
+  ]
+  dict = "//testing/libfuzzer/fuzzers/dicts/png.dict"
+  seed_corpus = "//third_party/WebKit/LayoutTests/images/resources/pngfuzz"
+}
+
 # Fuzzer for blink::JSONParser.
 fuzzer_test("blink_json_parser_fuzzer") {
   sources = [