Chrome: Export needed symbols to avoid direct external dependencies on protozero files

Without this, as the generated protozero files depend on src/protozero sourcesets,
we get ODR violations in Chrome component builds.

Bug: 78791178
Change-Id: I26b034e0fb15b406f4b38e7f1513f64df144b63f
diff --git a/BUILD.gn b/BUILD.gn
index 263ba08..22adbc5 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -230,6 +230,8 @@
     configs += [ "//build/config/compiler:no_chromium_code" ]
     public_deps = [
       "include/perfetto/tracing/core",
+      "protos/perfetto/trace:zero",
+      "protos/perfetto/trace/chrome:zero",
     ]
   }
 }