Proof of concept that CSSPropertyAPI*::parseSingleValue may need more tahn 2 arguments

third_party/WebKit/Source/core/css/BUILD.gn

 # Copyright 2016 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("//third_party/WebKit/Source/core/core.gni")
 
 blink_core_sources("css") {
   split_count = 5
   sources = [
     "ActiveStyleSheets.cpp",
@@ skipping 326 matching lines @@
     "parser/CSSSupportsParser.h",
     "parser/CSSTokenizer.cpp",
     "parser/CSSTokenizerInputStream.cpp",
     "parser/CSSVariableParser.cpp",
     "parser/CSSVariableParser.h",
     "parser/MediaQueryBlockWatcher.cpp",
     "parser/MediaQueryParser.cpp",
     "parser/SizesAttributeParser.cpp",
     "parser/SizesCalcParser.cpp",
     "properties/CSSPropertyAPI.h",
+    "properties/CSSPropertyAPIBackgroundComponent.cpp",
     "properties/CSSPropertyAPIBorderRadius.cpp",
     "properties/CSSPropertyAPICaretColor.cpp",
     "properties/CSSPropertyAPIClip.cpp",
     "properties/CSSPropertyAPIColumnGap.cpp",
     "properties/CSSPropertyAPIContain.cpp",
     "properties/CSSPropertyAPIContent.cpp",
     "properties/CSSPropertyAPICursor.cpp",
     "properties/CSSPropertyAPIFlexBasis.cpp",
     "properties/CSSPropertyAPIFontSizeAdjust.cpp",
     "properties/CSSPropertyAPIFontVariantCaps.cpp",
@@ skipping 88 matching lines @@
     "resolver/TransformBuilder.h",
     "resolver/ViewportStyleResolver.cpp",
     "resolver/ViewportStyleResolver.h",
   ]
 
   configs += [
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     "//build/config/compiler:no_size_t_to_int_warning",
   ]
 }