Add print event to perfetto_trace.proto

Bug: 114725477
Change-Id: I626df9515b9aa9f035fa0c39920e149891b04af5
diff --git a/tools/gen_merged_protos b/tools/gen_merged_protos
index 102ea4b..77bab2b 100755
--- a/tools/gen_merged_protos
+++ b/tools/gen_merged_protos
@@ -41,6 +41,10 @@
   'protos/perfetto/trace/filesystem/inode_file_map.proto',
   'protos/perfetto/trace/ps/process_tree.proto',
 
+  # Print proto is special: it doesn't have a enable file so is
+  # not present in genfs_contexts.
+  'protos/perfetto/trace/ftrace/print.proto',
+
   # FTrace events
   # Generated by tools/protos_from_genfs_contexts.sh.
   # MISSING cpufreq_interactive_load_change