Build pdfium_test executable under GN.

This is the second side of a two-sided patch and depends on:
  https://codereview.chromium.org/720193004/ - pdfium-side patch.
  https://codereview.chromium.org/733513002/ - pdfium roll.
  https://codereview.chromium.org/726033002/ - second pdfium-side patch.
  https://codereview.chromium.org/729623002/ - second pdfium roll.

Review URL: https://codereview.chromium.org/726003002

Cr-Commit-Position: refs/heads/master@{#304291}

1 files changed, 1 insertions, 0 deletions

diff --git a/BUILD.gn b/BUILD.gn
index 3b155cf..cba7efa 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -263,6 +263,7 @@ group("root") {
   if (!is_android && !is_ios) {
     deps += [
       "//device/usb",
+      "//third_party/pdfium/samples",
     ]
   }