android: Add thread time to early TraceEvent, make timings more precise.

base/trace_event/trace_event.h

Index: base/trace_event/trace_event.h
diff --git a/base/trace_event/trace_event.h b/base/trace_event/trace_event.h
index 07fd84157ed8c6cfb676e4c13b7ec1a87f4d44b2..f4eaac6ac3ff9378fc2ce1c49b02e2c5db1d01c8 100644
--- a/base/trace_event/trace_event.h
+++ b/base/trace_event/trace_event.h
@@ -183,6 +183,16 @@
 #define TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION \
     base::trace_event::TraceLog::GetInstance()->UpdateTraceEventDuration
 
+// Set the duration field of a COMPLETE trace event.
+// void TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION_EXPLICIT(
+//     const unsigned char* category_group_enabled,
+//     const char* name,
+//     base::trace_event::TraceEventHandle id,
+//     const TimeTicks& now,
+//     const ThreadTicks* thread_now)
+#define TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION_EXPLICIT \
+  base::trace_event::TraceLog::GetInstance()->UpdateTraceEventDurationExplicit
+
 // Adds a metadata event to the trace log. The |AppendValueAsTraceFormat| method
 // on the convertable value will be called at flush time.
 // TRACE_EVENT_API_ADD_METADATA_EVENT(
@@ -339,6 +349,32 @@
     }                                                                    \
   } while (0)
 
+// Implementation detail: internal macro to create static category and add
+// event if the category is enabled.
+#define INTERNAL_TRACE_EVENT_ADD_WITH_ID_TID_AND_TIMESTAMPS(                \
+    category_group, name, id, thread_id, begin_timestamp, end_timestamp,    \
+    thread_end_timestamp, flags, ...)                                       \
+  do {                                                                      \
+    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                 \
+    if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED()) {                    \
+      trace_event_internal::TraceID trace_event_trace_id((id));             \
+      unsigned int trace_event_flags =                                      \
+          flags | trace_event_trace_id.id_flags();                          \
+      const unsigned char* uid_category_group_enabled =                     \
+          INTERNAL_TRACE_EVENT_UID(category_group_enabled);                 \
+      auto handle =                                                         \
+          trace_event_internal::AddTraceEventWithThreadIdAndTimestamp(      \
+              TRACE_EVENT_PHASE_COMPLETE, uid_category_group_enabled, name, \
+              trace_event_trace_id.scope(), trace_event_trace_id.raw_id(),  \
+              thread_id, begin_timestamp,                                   \
+              trace_event_flags | TRACE_EVENT_FLAG_EXPLICIT_TIMESTAMP,      \
+              trace_event_internal::kNoId, ##__VA_ARGS__);                  \
+      TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION_EXPLICIT(                 \

[Primiano Tucci (use gerrit), 2017/07/10 13:09:15]

(mostly note to future-myself and git archaeologist): ah yeah, I see the problem
here. Having to leverage the after-the-fact update is a bit awkward (I wished we
never had that feature) but, at the same time, the alternative here would be
adding a new set of N new internal::AddTraceEventWithThreadIdAndTimestamp*s*
functions (one for each combination of argument types) and then change TraceLog,
which would make this CL and the resulting trace_event.h incredibly more complex
and unreadable. Pragmatism wins.

+          uid_category_group_enabled, name, handle, end_timestamp,          \
+          thread_end_timestamp);                                            \
+    }                                                                       \
+  } while (0)
+
 // The linked ID will not be mangled.
 #define INTERNAL_TRACE_EVENT_ADD_LINK_IDS(category_group, name, id1, id2) \
   do {                                                                    \