Make CPDF_ClipPath have a CPDF_ClipPathData rather than inheriting

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("//build_overrides/v8.gni")
 import("//testing/test.gni")
 import("pdfium.gni")
 
 config("pdfium_common_config") {
   cflags = []
@@ skipping 390 matching lines @@
     "core/fpdfapi/fpdf_font/font_int.h",
     "core/fpdfapi/fpdf_font/fpdf_font.cpp",
     "core/fpdfapi/fpdf_font/fpdf_font_cid.cpp",
     "core/fpdfapi/fpdf_font/include/cpdf_font.h",
     "core/fpdfapi/fpdf_font/include/cpdf_fontencoding.h",
     "core/fpdfapi/fpdf_font/ttgsubtable.cpp",
     "core/fpdfapi/fpdf_font/ttgsubtable.h",
     "core/fpdfapi/fpdf_page/cpdf_allstates.cpp",
     "core/fpdfapi/fpdf_page/cpdf_allstates.h",
     "core/fpdfapi/fpdf_page/cpdf_clippath.cpp",
-    "core/fpdfapi/fpdf_page/cpdf_clippathdata.cpp",
-    "core/fpdfapi/fpdf_page/cpdf_clippathdata.h",
     "core/fpdfapi/fpdf_page/cpdf_color.cpp",
     "core/fpdfapi/fpdf_page/cpdf_colorspace.cpp",
     "core/fpdfapi/fpdf_page/cpdf_colorstate.cpp",
     "core/fpdfapi/fpdf_page/cpdf_colorstate.h",
     "core/fpdfapi/fpdf_page/cpdf_colorstatedata.cpp",
     "core/fpdfapi/fpdf_page/cpdf_colorstatedata.h",
     "core/fpdfapi/fpdf_page/cpdf_contentmark.cpp",
     "core/fpdfapi/fpdf_page/cpdf_contentmark.h",
     "core/fpdfapi/fpdf_page/cpdf_contentmarkdata.cpp",
     "core/fpdfapi/fpdf_page/cpdf_contentmarkdata.h",
@@ skipping 1294 matching lines @@
 }
 
 if (pdf_is_standalone) {
   source_set("samples") {
     testonly = true
     deps = [
       "//samples",
     ]
   }
 }