Use SkPngEncoder and SkWebpEncoder in WebKit platform

third_party/WebKit/Source/platform/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("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 import("//testing/test.gni")
 import("//third_party/WebKit/public/public_features.gni")
 import("//third_party/WebKit/Source/build/scripts/scripts.gni")
@@ skipping 1133 matching lines @@
     "image-decoders/png/PNGImageDecoder.cpp",
     "image-decoders/png/PNGImageDecoder.h",
     "image-decoders/png/PNGImageReader.cpp",
     "image-decoders/png/PNGImageReader.h",
     "image-decoders/webp/WEBPImageDecoder.cpp",
     "image-decoders/webp/WEBPImageDecoder.h",
     "image-encoders/ImageEncoder.cpp",
     "image-encoders/ImageEncoder.h",
     "image-encoders/ImageEncoderUtils.cpp",
     "image-encoders/ImageEncoderUtils.h",
-    "image-encoders/PNGImageEncoder.cpp",
-    "image-encoders/PNGImageEncoder.h",
-    "image-encoders/WEBPImageEncoder.cpp",
-    "image-encoders/WEBPImageEncoder.h",
     "instrumentation/PlatformInstrumentation.cpp",
     "instrumentation/PlatformInstrumentation.h",
     "instrumentation/tracing/MemoryCacheDumpProvider.cpp",
     "instrumentation/tracing/MemoryCacheDumpProvider.h",
     "instrumentation/tracing/TraceEvent.h",
     "instrumentation/tracing/TracedValue.cpp",
     "instrumentation/tracing/TracedValue.h",
     "instrumentation/tracing/web_memory_allocator_dump.cc",
     "instrumentation/tracing/web_memory_allocator_dump.h",
     "instrumentation/tracing/web_process_memory_dump.cc",
@@ skipping 1070 matching lines @@
     "//third_party/WebKit/Source:config",
     "//third_party/WebKit/Source:inside_blink",
   ]
 
   deps = [
     ":test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }