Roll pdfium, add GN build for pdf and pdfium.

build/config/gcc/BUILD.gn

 # Copyright 2014 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.
 
 # This config causes functions not to be automatically exported from shared
 # libraries. By default, all symbols are exported but this means there are
 # lots of exports that slow everything down. In general we explicitly mark
 # which functiosn we want to export from components.
 #
 # Some third_party code assumes all functions are exported so this is separated
@@ skipping 17 matching lines @@
     "-Wl,-rpath-link=lib/",
   ]
 
   if (is_android) {
     ldflags += [
       "-Bdynamic",
       "-Wl,-z,nocopyreloc",
     ]
   }
 }
+
+config("no_exceptions") {
+  cflags_cc = [ "-fno-exceptions" ]
+}