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

base/trace_event/common/trace_event_common.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This header file defines the set of trace_event macros without specifying
 // how the events actually get collected and stored. If you need to expose trace
 // events to some other universe, you can copy-and-paste this file as well as
 // trace_event.h, modifying the macros contained there as necessary for the
 // target platform. The end result is that multiple libraries can funnel events
 // through to a shared trace event collector.
@@ skipping 916 matching lines @@
                                    arg1_val, arg2_name, arg2_val)
 
 // Special trace event macro to trace task execution with the location where it
 // was posted from.
 #define TRACE_TASK_EXECUTION(run_function, task) \
   INTERNAL_TRACE_TASK_EXECUTION(run_function, task)
 
 // 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.
 #define TRACE_EVENT_OBJECT_CREATED_WITH_ID(category_group, name, id) \
   INTERNAL_TRACE_EVENT_ADD_WITH_ID(                                  \
       TRACE_EVENT_PHASE_CREATE_OBJECT, category_group, name,         \
       TRACE_ID_DONT_MANGLE(id), TRACE_EVENT_FLAG_NONE)
 
 #define TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(category_group, name, id, \
                                             snapshot)                 \
@@ skipping 125 matching lines @@
 
 // Enum reflecting the scope of an INSTANT event. Must fit within
 // TRACE_EVENT_FLAG_SCOPE_MASK.
 #define TRACE_EVENT_SCOPE_GLOBAL (static_cast<unsigned char>(0 << 3))
 #define TRACE_EVENT_SCOPE_PROCESS (static_cast<unsigned char>(1 << 3))
 #define TRACE_EVENT_SCOPE_THREAD (static_cast<unsigned char>(2 << 3))
 
 #define TRACE_EVENT_SCOPE_NAME_GLOBAL ('g')
 #define TRACE_EVENT_SCOPE_NAME_PROCESS ('p')
 #define TRACE_EVENT_SCOPE_NAME_THREAD ('t')