Tracing: Added necessary plumbing to make sure clocksync metadata events are always included.

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 0a04d627108c773755c5bdebf4fb897afc8d392f..eb0fbae8af6585c0c15ba5fbfc3d30fdfbb086b0 100644
--- a/base/trace_event/common/trace_event_common.h
+++ b/base/trace_event/common/trace_event_common.h
@@ -934,18 +934,22 @@
 // TRACE_EVENT_METADATA* events are information related to other
 // injected events, not events in their own right.
 #define TRACE_EVENT_METADATA1(category_group, name, arg1_name, arg1_val) \
-  INTERNAL_TRACE_EVENT_METADATA_ADD(category_group, name, arg1_name, arg1_val)
+  INTERNAL_TRACE_EVENT_METADATA_ADD_IF_ENABLED(category_group, name,     \
+                                               arg1_name, arg1_val)
 
+#define TRACE_EVENT_METADATA_FORCED1(name, arg1_name, arg1_val)              \
+  INTERNAL_TRACE_EVENT_METADATA_ADD_FORCED(TRACE_EVENT_PHASE_METADATA, name, \
+                                           arg1_name, arg1_val)
 // Records a clock sync event.
-#define TRACE_EVENT_CLOCK_SYNC_RECEIVER(sync_id)                               \
-  INTERNAL_TRACE_EVENT_ADD(                                                    \
-      TRACE_EVENT_PHASE_CLOCK_SYNC, "__metadata", "clock_sync",                \
-      TRACE_EVENT_FLAG_NONE, "sync_id", sync_id)
-#define TRACE_EVENT_CLOCK_SYNC_ISSUER(sync_id, issue_ts, issue_end_ts)         \
-  INTERNAL_TRACE_EVENT_ADD_WITH_TIMESTAMP(                                     \
-      TRACE_EVENT_PHASE_CLOCK_SYNC, "__metadata", "clock_sync",                \
-      issue_end_ts.ToInternalValue(), TRACE_EVENT_FLAG_NONE,                   \
-      "sync_id", sync_id, "issue_ts", issue_ts.ToInternalValue())
+#define TRACE_EVENT_CLOCK_SYNC_RECEIVER(sync_id)                         \
+  INTERNAL_TRACE_EVENT_METADATA_ADD_FORCED(TRACE_EVENT_PHASE_CLOCK_SYNC, \
+                                           "clock_sync", "sync_id", sync_id)
+
+#define TRACE_EVENT_CLOCK_SYNC_ISSUER(sync_id, issue_ts, issue_end_ts) \
+  INTERNAL_TRACE_EVENT_METADATA_ADD_FORCED_WITH_TIMESTAMP(             \
+      TRACE_EVENT_PHASE_CLOCK_SYNC, "clock_sync",                      \
+      issue_end_ts.ToInternalValue(), "sync_id", sync_id, "issue_ts",  \
+      issue_ts.ToInternalValue())
 
 // Macros to track the life time and value of arbitrary client objects.
 // See also TraceTrackableObject.