Add a Retained Pointer smart class.

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_config") {
   cflags = []
@@ skipping 597 matching lines @@
     "core/fxcrt/fx_unicode.cpp",
     "core/fxcrt/fx_xml_composer.cpp",
     "core/fxcrt/fx_xml_parser.cpp",
     "core/fxcrt/fxcrt_platforms.cpp",
     "core/fxcrt/fxcrt_platforms.h",
     "core/fxcrt/fxcrt_posix.cpp",
     "core/fxcrt/fxcrt_posix.h",
     "core/fxcrt/fxcrt_stream.cpp",
     "core/fxcrt/fxcrt_windows.cpp",
     "core/fxcrt/fxcrt_windows.h",
+    "core/fxcrt/include/cfx_retain_ptr.h",
     "core/fxcrt/include/fx_basic.h",
     "core/fxcrt/include/fx_coordinates.h",
     "core/fxcrt/include/fx_ext.h",
     "core/fxcrt/include/fx_memory.h",
     "core/fxcrt/include/fx_safe_types.h",
     "core/fxcrt/include/fx_stream.h",
     "core/fxcrt/include/fx_string.h",
     "core/fxcrt/include/fx_system.h",
     "core/fxcrt/include/fx_ucd.h",
     "core/fxcrt/include/fx_xml.h",
@@ skipping 959 matching lines @@
     "core/fpdfapi/fpdf_font/fpdf_font_unittest.cpp",
     "core/fpdfapi/fpdf_page/fpdf_page_parser_old_unittest.cpp",
     "core/fpdfapi/fpdf_parser/cpdf_object_unittest.cpp",
     "core/fpdfapi/fpdf_parser/cpdf_parser_unittest.cpp",
     "core/fpdfapi/fpdf_parser/cpdf_simple_parser_unittest.cpp",
     "core/fpdfapi/fpdf_parser/cpdf_syntax_parser_unittest.cpp",
     "core/fpdfapi/fpdf_parser/fpdf_parser_decode_unittest.cpp",
     "core/fpdfdoc/doc_basic_unittest.cpp",
     "core/fpdftext/fpdf_text_int_unittest.cpp",
     "core/fxcodec/codec/fx_codec_jpx_unittest.cpp",
+    "core/fxcrt/cfx_retain_ptr_unittest.cpp",
     "core/fxcrt/fx_basic_bstring_unittest.cpp",
     "core/fxcrt/fx_basic_gcc_unittest.cpp",
     "core/fxcrt/fx_basic_memmgr_unittest.cpp",
     "core/fxcrt/fx_basic_wstring_unittest.cpp",
     "core/fxcrt/fx_bidi_unittest.cpp",
     "core/fxcrt/fx_extension_unittest.cpp",
     "core/fxcrt/fx_system_unittest.cpp",
     "fpdfsdk/fpdfdoc_unittest.cpp",
   ]
   deps = [
@@ skipping 62 matching lines @@
       "//v8:v8_libplatform",
     ]
     include_dirs += [
       "//v8",
       "//v8/include",
     ]
     configs += [ "//v8:external_startup_data" ]
   }
   configs += [ ":pdfium_config" ]
 }