feat: enable pdf viewer (#21794)

patches/chromium/use_electron_resources_in_pdf_util.patch

@@ -0,0 +1,22 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jeremy Apthorp <nornagon@nornagon.net>
+Date: Mon, 10 Feb 2020 10:37:48 -0800
+Subject: use electron resources in pdf_util
+
+Without this, the ID for IDR_PDF_MANIFEST will be wrong on linux
+and cause a DCHECK(), since the resource will be loaded as an empty
+string.
+
+diff --git a/chrome/browser/pdf/pdf_extension_util.cc b/chrome/browser/pdf/pdf_extension_util.cc
+index 877d0ba2f48359243527ddebf1d91132b3d5c455..cd69de498c4968ade0ffabf45b72d4d63b70b10f 100644
+--- a/chrome/browser/pdf/pdf_extension_util.cc
++++ b/chrome/browser/pdf/pdf_extension_util.cc
+@@ -6,7 +6,7 @@
+ 
+ #include "base/strings/string_util.h"
+ #include "chrome/common/chrome_content_client.h"
+-#include "chrome/grit/browser_resources.h"
++#include "electron/grit/electron_resources.h"
+ #include "ui/base/resource/resource_bundle.h"
+ 
+ namespace pdf_extension_util {