Make some third_party targets pass gn check.

Change-Id: I2b4b011a242db8ab43634c4e057d6d2b6d4f8c24
Reviewed-on: https://pdfium-review.googlesource.com/c/44079
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/.gn b/.gn
index c1849a0f73..b302768c02 100644
--- a/.gn
+++ b/.gn
@@ -30,5 +30,10 @@ check_targets = [
   "//testing/:*",
   "//testing/fuzzers/*",
   "//testing/image_diff/*",
+  "//third_party:bigint",
+  "//third_party:fx_agg",
+  "//third_party:fx_freetype",
+  "//third_party:pdfium_base",
+  "//third_party:skia_shared",
   "//xfa/*",
 ]