Enable Wshift-negative-value in PDFium.

BUG=chromium:507717

Change-Id: If0030640497ce103de7713f8497570602950a2b6
Reviewed-on: https://pdfium-review.googlesource.com/3270
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
diff --git a/third_party/BUILD.gn b/third_party/BUILD.gn
index cabd7af..e1076ee 100644
--- a/third_party/BUILD.gn
+++ b/third_party/BUILD.gn
@@ -195,21 +195,11 @@
 }
 
 # This is only used for standalone builds.
-config("jpeg_warnings") {
-  visibility = [ ":*" ]
-  if (is_clang) {
-    cflags = [ "-Wno-shift-negative-value" ]
-  }
-}
-
 static_library("jpeg") {
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [
     "//build/config/compiler:no_chromium_code",
     ":pdfium_third_party_config",
-
-    # Must be after no_chromium_code for warning flags to be ordered correctly.
-    ":jpeg_warnings",
   ]
   sources = [
     "libjpeg/cderror.h",