Fix Observatory timeline export to be compatible with about:tracing

runtime/vm/profiler_service.cc

Index: runtime/vm/profiler_service.cc
diff --git a/runtime/vm/profiler_service.cc b/runtime/vm/profiler_service.cc
index 6731e2d91d8f167723070a34cc0871c441943999..679847aebe65df02c0df3a1ccd59f71c0362ac79 100644
--- a/runtime/vm/profiler_service.cc
+++ b/runtime/vm/profiler_service.cc
@@ -2419,6 +2419,8 @@ void Profile::PrintTimelineJSON(JSONStream* stream) {
       ProcessedSample* sample = samples_->At(sample_index);
       JSONObject event(&events);
       event.AddProperty("ph", "P");  // kind = sample event
+      // Add a blank name to keep about:tracing happy.
+      event.AddProperty("name", "");
       event.AddProperty64("pid", pid);
       event.AddProperty64("tid", OSThread::ThreadIdToIntPtr(sample->tid()));
       event.AddPropertyTimeMicros("ts", sample->timestamp());