Binds two IDs together.

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.
 
 #ifndef BASE_TRACE_EVENT_TRACE_EVENT_H_
 #define BASE_TRACE_EVENT_TRACE_EVENT_H_
 
 // This header file defines implementation details of how the trace macros in
 // trace_event_common.h collect and store trace events. Anything not
 // implementation-specific should go in trace_event_common.h instead of here.
@@ skipping 331 matching lines @@
                                                          &trace_event_flags); \
       trace_event_internal::AddTraceEventWithThreadIdAndTimestamp(            \
           phase, INTERNAL_TRACE_EVENT_UID(category_group_enabled), name,      \
           trace_event_trace_id.scope(), trace_event_trace_id.raw_id(),        \
           thread_id, base::TimeTicks::FromInternalValue(timestamp),           \
           trace_event_flags | TRACE_EVENT_FLAG_EXPLICIT_TIMESTAMP,            \
           trace_event_internal::kNoId, ##__VA_ARGS__);                        \
     }                                                                         \
   } while (0)
 
+// The trace ID and bind ID will never be mangled by this macro.
+#define INTERNAL_TRACE_EVENT_ADD_BIND_IDS(category_group, name, id, bind_id,  \
+                                          ...)                                \
+    do {                                                                      \
+      INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                 \
+      if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
+        unsigned int dummy_flags = TRACE_EVENT_FLAG_NONE;                     \
+        trace_event_internal::TraceID trace_event_trace_id(id, &dummy_flags); \

[Primiano Tucci (use gerrit), 2016/07/20 16:39:04]

I think you don't need dummy_flags here and just use TraceID::DontMangle(id)

[chiniforooshan, 2016/07/20 18:41:36]

Done.

+        trace_event_internal::TraceID trace_event_bind_id(                    \

[Primiano Tucci (use gerrit), 2016/07/20 16:39:04]

maybe calling these vars "source_id" and "target_id" instad of "trace_id" and
"bind_id" makes it easier to reason about?

[chiniforooshan, 2016/07/20 18:41:36]

Done.

+            bind_id, &dummy_flags);                                           \
+        if (trace_event_bind_id.scope() ==                                    \
+            trace_event_internal::kGlobalScope) {                             \
+          trace_event_internal::AddTraceEvent(                                \
+              TRACE_EVENT_PHASE_BIND_IDS,                                     \
+              INTERNAL_TRACE_EVENT_UID(category_group_enabled),               \
+              name, trace_event_trace_id.scope(),                             \
+              trace_event_trace_id.raw_id(),                                  \
+              TRACE_EVENT_FLAG_HAS_ID, trace_event_bind_id.raw_id(),          \
+              ##__VA_ARGS__);                                                 \
+        } else {                                                              \
+          trace_event_internal::AddTraceEvent(                                \
+              TRACE_EVENT_PHASE_BIND_IDS,                                     \
+              INTERNAL_TRACE_EVENT_UID(category_group_enabled),               \
+              name, trace_event_trace_id.scope(),                             \
+              trace_event_trace_id.raw_id(),                                  \
+              TRACE_EVENT_FLAG_HAS_ID, trace_event_bind_id.raw_id(),          \
+              "bind_scope", trace_event_bind_id.scope(), ##__VA_ARGS__);      \

[Primiano Tucci (use gerrit), 2016/07/20 16:39:04]

same here, I'd call this arg "target_scope" or "target_bind_scope" or
"bind_target_scope"

[chiniforooshan, 2016/07/20 18:41:36]

I changed the local variable names to {source, target}_id. But, I think it's
better to keep field name "bind_scope" in the args of the actual JSON event,
because we are stuck with the "bind_id" field name at least until tracing V2.

+        }                                                                     \
+      }                                                                       \
+    } while (0)
+
 // Implementation detail: internal macro to create static category and add
 // metadata event if the category is enabled.
 #define INTERNAL_TRACE_EVENT_METADATA_ADD(category_group, name, ...)        \
   do {                                                                      \
     INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                 \
     if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
       TRACE_EVENT_API_ADD_METADATA_EVENT(                                   \
           INTERNAL_TRACE_EVENT_UID(category_group_enabled), name,           \
           ##__VA_ARGS__);                                                   \
     }                                                                       \
@@ skipping 721 matching lines @@
   const char* name_;
   IDType id_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceScopedTrackableObject);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_H_