Change sampler code events phase from instant to meta.

base/trace_event/trace_event.h

 // Copyright (c) 2012 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 537 matching lines @@
       TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
 
 #define TRACE_EVENT_SAMPLE_WITH_TID_AND_TIMESTAMP2(category_group, name,       \
                                                    thread_id, timestamp,       \
                                                    arg1_name, arg1_val,        \
                                                    arg2_name, arg2_val)        \
   INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMP(                          \
       TRACE_EVENT_PHASE_SAMPLE, category_group, name, 0, thread_id, timestamp, \
       TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val, arg2_name, arg2_val)
 
+// TRACE_EVENT_METADATA* events are injected by the sampling profiler.

[dsinclair, 2015/07/02 14:17:05]

nit: remove the bit about being injected by the profile and say something like.
'events are information related to other injected events, not events in their
own right'.

[alph, 2015/07/02 14:59:55]

Done. Thanks.

+#define TRACE_EVENT_METADATA0(category_group, name)                          \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_METADATA, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE)
+#define TRACE_EVENT_METADATA1(category_group, name, arg1_name, arg1_val)     \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_METADATA, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val)
+#define TRACE_EVENT_METADATA2(category_group, name, arg1_name, arg1_val,     \
+                              arg2_name, arg2_val)                           \
+  INTERNAL_TRACE_EVENT_ADD(TRACE_EVENT_PHASE_METADATA, category_group, name, \
+                           TRACE_EVENT_FLAG_NONE, arg1_name, arg1_val,       \
+                           arg2_name, arg2_val)
+
 // ASYNC_STEP_* APIs should be only used by legacy code. New code should
 // consider using NESTABLE_ASYNC_* APIs to describe substeps within an async
 // event.
 // Records a single ASYNC_BEGIN event called "name" immediately, with 0, 1 or 2
 // associated arguments. If the category is not enabled, then this
 // does nothing.
 // - category and name strings must have application lifetime (statics or
 //   literals). They may not include " chars.
 // - |id| is used to match the ASYNC_BEGIN event with the ASYNC_END event. ASYNC
 //   events are considered to match if their category_group, name and id values
@@ skipping 1148 matching lines @@
   const char* name_;
   IDType id_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceScopedTrackableObject);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_H_