Remove IFGAS_FontMgr and clean up (the renamed) CFGAS_FontMgr a little.

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 1127 matching lines @@
       "xfa/fde/xml/fde_xml_imp.h",
       "xfa/fgas/crt/fgas_codepage.cpp",
       "xfa/fgas/crt/fgas_codepage.h",
       "xfa/fgas/crt/fgas_language.h",
       "xfa/fgas/crt/fgas_memory.cpp",
       "xfa/fgas/crt/fgas_memory.h",
       "xfa/fgas/crt/fgas_stream.cpp",
       "xfa/fgas/crt/fgas_stream.h",
       "xfa/fgas/crt/fgas_utils.cpp",
       "xfa/fgas/crt/fgas_utils.h",
-      "xfa/fgas/font/fgas_font.h",
+      "xfa/fgas/font/cfgas_fontmgr.cpp",
+      "xfa/fgas/font/cfgas_fontmgr.h",
       "xfa/fgas/font/fgas_fontutils.cpp",
       "xfa/fgas/font/fgas_fontutils.h",
       "xfa/fgas/font/fgas_gefont.cpp",
       "xfa/fgas/font/fgas_gefont.h",
-      "xfa/fgas/font/fgas_stdfontmgr.cpp",
-      "xfa/fgas/font/fgas_stdfontmgr.h",
       "xfa/fgas/layout/fgas_linebreak.cpp",
       "xfa/fgas/layout/fgas_linebreak.h",
       "xfa/fgas/layout/fgas_rtfbreak.cpp",
       "xfa/fgas/layout/fgas_rtfbreak.h",
       "xfa/fgas/layout/fgas_textbreak.cpp",
       "xfa/fgas/layout/fgas_textbreak.h",
       "xfa/fgas/layout/fgas_unicode.cpp",
       "xfa/fgas/layout/fgas_unicode.h",
       "xfa/fgas/localization/fgas_datetime.cpp",
       "xfa/fgas/localization/fgas_datetime.h",
@@ skipping 607 matching lines @@
       "//samples",
     ]
   }
   group("fuzzers") {
     testonly = true
     deps = [
       "//testing/libfuzzer",
     ]
   }
 }