Make output of Dart_TimelineGetTrace consumable by mojo

runtime/vm/timeline.cc

Index: runtime/vm/timeline.cc
diff --git a/runtime/vm/timeline.cc b/runtime/vm/timeline.cc
index c24cc2b3c347f150cb751bc23f63c2a404f2fb6e..22e601fa4b4af5c2049840591385b4d5e871be01 100644
--- a/runtime/vm/timeline.cc
+++ b/runtime/vm/timeline.cc
@@ -681,6 +681,13 @@ void TimelineEventRingRecorder::PrintJSON(JSONStream* js,
 }
 
 
+void TimelineEventRingRecorder::PrintTraceEvent(JSONStream* js,
+                                                TimelineEventFilter* filter) {
+  JSONArray events(js);
+  PrintJSONEvents(&events, filter);
+}
+
+
 TimelineEventBlock* TimelineEventRingRecorder::GetHeadBlockLocked() {
   return blocks_[0];
 }
@@ -747,6 +754,13 @@ void TimelineEventStreamingRecorder::PrintJSON(JSONStream* js,
 }
 
 
+void TimelineEventStreamingRecorder::PrintTraceEvent(
+    JSONStream* js,
+    TimelineEventFilter* filter) {
+  JSONArray events(js);
+}
+
+
 TimelineEvent* TimelineEventStreamingRecorder::StartEvent() {
   TimelineEvent* event = new TimelineEvent();
   return event;
@@ -778,6 +792,14 @@ void TimelineEventEndlessRecorder::PrintJSON(JSONStream* js,
 }
 
 
+void TimelineEventEndlessRecorder::PrintTraceEvent(
+    JSONStream* js,
+    TimelineEventFilter* filter) {
+  JSONArray events(js);
+  PrintJSONEvents(&events, filter);
+}
+
+
 TimelineEventBlock* TimelineEventEndlessRecorder::GetHeadBlockLocked() {
   return head_;
 }