Added CSSPropertyBackgroundComponentUtils which holds background component parsing methods.

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 374 matching lines @@
     "properties/CSSPropertyAPIWebkitHighlight.cpp",
     "properties/CSSPropertyAPIWebkitLineClamp.cpp",
     "properties/CSSPropertyAPIWebkitPadding.cpp",
     "properties/CSSPropertyAPIWebkitTextEmphasisStyle.cpp",
     "properties/CSSPropertyAPIWebkitTransformOriginZ.cpp",
     "properties/CSSPropertyAPIWillChange.cpp",
     "properties/CSSPropertyAPIZIndex.cpp",
     "properties/CSSPropertyAPIZoom.cpp",
     "properties/CSSPropertyAlignmentUtils.cpp",
     "properties/CSSPropertyAlignmentUtils.h",
+    "properties/CSSPropertyBackgroundComponentUtils.cpp",
+    "properties/CSSPropertyBackgroundComponentUtils.h",
     "properties/CSSPropertyColumnUtils.cpp",
     "properties/CSSPropertyColumnUtils.h",
     "properties/CSSPropertyDescriptor.h",
     "properties/CSSPropertyLengthUtils.cpp",
     "properties/CSSPropertyLengthUtils.h",
     "properties/CSSPropertyShapeUtils.cpp",
     "properties/CSSPropertyShapeUtils.h",
     "resolver/AnimatedStyleBuilder.cpp",
     "resolver/AnimatedStyleBuilder.h",
     "resolver/CSSToStyleMap.cpp",
@@ skipping 38 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",
   ]
 }