Add missing dependency for interceptor_trace_writer_unittest.cc

This showed up only on some platforms/envs for Chromium.

Bug: 230715593
Change-Id: I3248dde819ba0a82f890ef36fb9205d04152c353
diff --git a/src/tracing/BUILD.gn b/src/tracing/BUILD.gn
index 4f5ae53..5635c56 100644
--- a/src/tracing/BUILD.gn
+++ b/src/tracing/BUILD.gn
@@ -138,6 +138,7 @@
 perfetto_unittest_source_set("unittests") {
   testonly = true
   deps = [
+    "../../gn:default_deps",
     "../../gn:gtest_and_gmock",
     "../../protos/perfetto/trace:lite",
     "../../protos/perfetto/trace/track_event:lite",