Add support for multiple frames in SkCodec

BUILD.gn

 # Copyright 2016 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("gn/shared_sources.gni")
 
 if (!defined(is_skia_standalone)) {
   is_skia_standalone = false
 }
 
 declare_args() {
   skia_use_angle = false
   skia_use_expat = true
   skia_use_fontconfig = is_linux
   skia_use_freetype = is_android || is_fuchsia || is_linux
-  skia_use_giflib = !is_fuchsia
   skia_use_libjpeg_turbo = true
   skia_use_libpng = true
   skia_use_libwebp = !is_fuchsia
   skia_use_mesa = false
   skia_use_sfntly = !is_fuchsia && !is_win  # TODO: icu on Windows, re-enable this.
   skia_use_vulkan = is_android && defined(ndk_api) && ndk_api >= 24
   skia_use_zlib = true
 
   skia_enable_android_framework_defines = false
   skia_enable_gpu = true
@@ skipping 303 matching lines @@
 
   deps = [
     "//third_party/freetype2",
   ]
   sources = [
     "src/ports/SkFontMgr_custom.cpp",
     "src/ports/SkFontMgr_custom_empty_factory.cpp",
   ]
 }
 
-optional("gif") {
-  enabled = skia_use_giflib
-  public_defines = [ "SK_HAS_GIF_LIBRARY" ]
-
-  deps = [
-    "//third_party/giflib",
-  ]
-  sources = [
-    "src/codec/SkGifCodec.cpp",
-  ]
-}
-
 optional("gpu") {
   enabled = skia_enable_gpu
   public_defines = []
 
   sources = skia_gpu_sources + [ "src/gpu/gl/GrGLDefaultInterface_native.cpp" ]
 
   # These paths need to be absolute to match the ones produced by shared_sources.gni.
   sources -= get_path_info([
                              "src/gpu/gl/GrGLCreateNativeInterface_none.cpp",
                              "src/gpu/gl/GrGLDefaultInterface_none.cpp",
@@ skipping 134 matching lines @@
   ]
 
   sources = []
   sources += skia_core_sources
   sources += skia_effects_sources
   sources += skia_sksl_sources
   sources += skia_utils_sources
   sources += [
     "src/android/SkBitmapRegionCodec.cpp",
     "src/android/SkBitmapRegionDecoder.cpp",
+    "src/codec/GIFImageDecoder.cpp",
     "src/codec/SkAndroidCodec.cpp",
     "src/codec/SkBmpCodec.cpp",
     "src/codec/SkBmpMaskCodec.cpp",
     "src/codec/SkBmpRLECodec.cpp",
     "src/codec/SkBmpStandardCodec.cpp",
     "src/codec/SkCodec.cpp",
     "src/codec/SkCodecImageGenerator.cpp",
+    "src/codec/SkGifCodec.cpp",
     "src/codec/SkMaskSwizzler.cpp",
     "src/codec/SkMasks.cpp",
     "src/codec/SkSampledCodec.cpp",
     "src/codec/SkSampler.cpp",
     "src/codec/SkSwizzler.cpp",
     "src/codec/SkWbmpCodec.cpp",
     "src/images/SkImageEncoder.cpp",
     "src/images/SkImageEncoder_Factory.cpp",
     "src/images/SkKTXImageEncoder.cpp",
     "src/ports/SkDiscardableMemory_none.cpp",
@@ skipping 519 matching lines @@
       "tools/DumpRecord.cpp",
       "tools/dump_record.cpp",
     ]
     deps = [
       ":flags",
       ":skia",
     ]
     testonly = true
   }
 }