mojo: Fix trace event mismatches in mojo sync methods

Use a new variable at interface_definition.tmpl:273 to ensure the
same event name is used for both trace BEGIN and END events.

Bug: 489897725
Change-Id: I1611c3af9e3b60c5836c7a3e0a711e06ea2f8093
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7613392
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1597456}
NOKEYCHECK=True
GitOrigin-RevId: f29f83c2405e00880989954ebfb451d4ca4a4090
diff --git a/golden/generated/c++/results.test-mojom.cc.golden b/golden/generated/c++/results.test-mojom.cc.golden
index ac55168..5b40804 100644
--- a/golden/generated/c++/results.test-mojom.cc.golden
+++ b/golden/generated/c++/results.test-mojom.cc.golden
@@ -482,7 +482,7 @@
   ::mojo::internal::SendMojoMessage(*receiver_, message, std::move(responder));
 #if BUILDFLAG(MOJO_TRACE_ENABLED)
   TRACE_EVENT_END1(
-    "mojom", "ResultInterface::SyncMethod", "sync_response_parameters",
+    "mojom", "Call golden::ResultInterface::SyncMethod (sync)", "sync_response_parameters",
     [&](perfetto::TracedValue context){
       auto dict = std::move(context).WriteDictionary();
       perfetto::WriteIntoTracedValueWithFallback(
diff --git a/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl b/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl
index fc403f9..85174a0 100644
--- a/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl
+++ b/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl
@@ -270,8 +270,8 @@
                                  trace_event_type='_BEGIN')}}
 #else
 {#- Output a minimal trace event if MOJO_TRACE_ENABLED is false. #}
-{%-     set event_name = "%s::%s" % (class_name, method.name) %}
-  {{interface_macros.trace_event(method_name=event_name)}}
+{%-     set short_event_name = "%s::%s" % (class_name, method.name) %}
+  {{interface_macros.trace_event(method_name=short_event_name)}}
 #endif
   {{check_feature_for_method(method)|indent(2)}}
   const bool kExpectsResponse = true;