Implements AddStartupEventsForTelemetry() in startup_metric_utils.cc for in-coming startup telemetry

base/trace_event/common/trace_event_common.h

Index: base/trace_event/common/trace_event_common.h
diff --git a/base/trace_event/common/trace_event_common.h b/base/trace_event/common/trace_event_common.h
index 33578bd37bd2583fb7c99cce4bb7ab14614906a2..99a41fe7b6a24d3a724b48f4da1cb7a30aa7ca8e 100644
--- a/base/trace_event/common/trace_event_common.h
+++ b/base/trace_event/common/trace_event_common.h
@@ -309,6 +309,12 @@
                            TRACE_EVENT_FLAG_COPY | scope, arg1_name, arg1_val, \
                            arg2_name, arg2_val)
 
+#define TRACE_EVENT_INSTANT_WITH_TIMESTAMP(category_group, name,          \
+                                           scope, timestamp)              \
+  INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                     \
+      TRACE_EVENT_PHASE_MARK, category_group, name, 0, 0, timestamp,      \
+      TRACE_EVENT_FLAG_NONE)
+
 // Syntactic sugars for the sampling tracing in the main thread.
 #define TRACE_EVENT_SCOPED_SAMPLING_STATE(category, name) \
   TRACE_EVENT_SCOPED_SAMPLING_STATE_FOR_BUCKET(0, category, name)