Match GN and GYP compilation warning flags

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 26 matching lines @@
       defines += [ "_FX_CPU_=_FX_X64_" ]
       cflags += [ "-fPIC" ]
     } else if (current_cpu == "x86") {
       defines += [ "_FX_CPU_=_FX_X86_" ]
     }
   }
 
   if (is_win) {
     cflags += [ "/wd4267" ]
   }
+}
 
-  if (is_clang || is_posix) {
-    # TODO(thestig): Fix all instances, remove this, pdfium:29
-    cflags += [ "-Wno-sign-compare" ]
-  }
-
+config("xfa_warnings") {
+  visibility = [ ":*" ]
   if (is_posix && !is_clang) {  # When GCC.
-    cflags += [ "-Wno-strict-overflow" ]
+    cflags = [ "-Wno-strict-overflow" ]
   }
 }
 
 static_library("pdfium") {
   sources = [
     "fpdfsdk/cfx_systemhandler.cpp",
     "fpdfsdk/cfx_systemhandler.h",
     "fpdfsdk/fpdf_dataavail.cpp",
     "fpdfsdk/fpdf_ext.cpp",
     "fpdfsdk/fpdf_flatten.cpp",
@@ skipping 816 matching lines @@
       "fpdfsdk/fpdfxfa/fpdfxfa_page.cpp",
       "fpdfsdk/fpdfxfa/fpdfxfa_util.cpp",
       "fpdfsdk/fpdfxfa/include/fpdfxfa_app.h",
       "fpdfsdk/fpdfxfa/include/fpdfxfa_doc.h",
       "fpdfsdk/fpdfxfa/include/fpdfxfa_page.h",
       "fpdfsdk/fpdfxfa/include/fpdfxfa_util.h",
     ]
     deps = [
       ":xfa",
     ]
-    configs -= [ "//build/config/compiler:chromium_code" ]
-    configs += [
-      ":pdfium_config",
-      "//build/config/compiler:no_chromium_code",
-    ]
+    configs += [ ":pdfium_config" ]
   }
 
   static_library("xfa") {
     sources = [
       "xfa/fde/cfde_path.cpp",
       "xfa/fde/cfde_path.h",
       "xfa/fde/cfde_txtedtbuf.cpp",
       "xfa/fde/cfde_txtedtbuf.h",
       "xfa/fde/cfde_txtedtbufiter.cpp",
       "xfa/fde/cfde_txtedtbufiter.h",
@@ skipping 680 matching lines @@
         "//v8",
         "//v8/include",
       ]
       public_deps = [
         "//v8",
       ]
       deps = [
         "//v8:v8_libplatform",
       ]
     }
-    configs -= [ "//build/config/compiler:chromium_code" ]
     configs += [
       ":pdfium_config",
-      "//build/config/compiler:no_chromium_code",
+      ":xfa_warnings",
     ]
   }
 }
 
 test("pdfium_unittests") {
   sources = [
     "core/fpdfapi/fpdf_font/fpdf_font_cid_unittest.cpp",
     "core/fpdfapi/fpdf_font/fpdf_font_unittest.cpp",
     "core/fpdfapi/fpdf_page/fpdf_page_parser_old_unittest.cpp",
     "core/fpdfapi/fpdf_page/fpdf_page_parser_unittest.cpp",
@@ skipping 97 matching lines @@
 }
 
 if (pdf_is_standalone) {
   source_set("samples") {
     testonly = true
     deps = [
       "//samples",
     ]
   }
 }