Add a missing enable_pdf conditional when building pdfium_test

The fuchsia-x64-cast-receiver-rel builder is still trying to build
pdfium_test, even though the enable_pdf GN arg is set to false. Add the
missing conditional to fix this issue.

Change-Id: I38623d7b3f2b9c922a16e09c9a21a2576d763f20
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5309762
Reviewed-by: Thomas Anderson <[email protected]>
Commit-Queue: Lei Zhang <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1262967}
diff --git a/BUILD.gn b/BUILD.gn
index a57476d..1e825fcf 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1689,10 +1689,10 @@
       deps += [ "//tools/ipc_fuzzer:ipc_fuzzer_all" ]
     }
     if (!is_chromeos_ash) {
-      deps += [
-        "//third_party/pdfium/samples:pdfium_test",
-        "//v8:v8_shell($v8_snapshot_toolchain)",
-      ]
+      deps += [ "//v8:v8_shell($v8_snapshot_toolchain)" ]
+      if (enable_pdf) {
+        deps += [ "//third_party/pdfium/samples:pdfium_test" ]
+      }
     }
 
     if (!is_component_build) {