Revert of Allow overriding GN build flags

pdfium.gni

Index: pdfium.gni
diff --git a/pdfium.gni b/pdfium.gni
new file mode 100644
index 0000000000000000000000000000000000000000..b85ac74d0f226d1712537b7141470b68f6fbb0d1
--- /dev/null
+++ b/pdfium.gni
@@ -0,0 +1,23 @@
+# Copyright 2015 PDFium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# This file contains PDFium-related build flags.
+
+declare_args() {
+  # On Android there's no system FreeType. On Windows and Mac, only a few
+  # methods are used from it.
+  pdfium_bundle_freetype = !is_linux
+
+  # Build PDFium either with or without v8 support.
+  pdf_enable_v8 = true
+
+  # Build PDFium either with or without XFA Forms support.
+  pdf_enable_xfa = false
+
+  # Build PDFium against skia (experimental) rather than agg.
+  pdf_use_skia = false
+
+  # Build PDFium standalone
+  pdf_is_standalone = false
+}