Implement a new flow event API that allows binding flow events and regular events.

base/trace_event/trace_event_impl.cc

Index: base/trace_event/trace_event_impl.cc
diff --git a/base/trace_event/trace_event_impl.cc b/base/trace_event/trace_event_impl.cc
index f01a8880400f3ed55bfe1e0196965d9f301b03b9..b6e17565a5cb4e0c6f5b969454c2f8a8764723f8 100644
--- a/base/trace_event/trace_event_impl.cc
+++ b/base/trace_event/trace_event_impl.cc
@@ -413,7 +413,7 @@ void InitializeMetadataEvent(TraceEvent* trace_event,
                           &g_category_group_enabled[g_category_metadata],
                           metadata_name, ::trace_event_internal::kNoEventId,
                           num_args, &arg_name, &arg_type, &arg_value, NULL,
-                          TRACE_EVENT_FLAG_NONE);
+                          TRACE_EVENT_FLAG_NONE, trace_event_internal::kNoBindId);
 }
 
 class AutoThreadLocalBoolean {
@@ -597,7 +597,8 @@ void TraceEvent::Initialize(
     const unsigned char* arg_types,
     const unsigned long long* arg_values,
     const scoped_refptr<ConvertableToTraceFormat>* convertable_values,
-    unsigned int flags) {
+    unsigned int flags,
+    unsigned long long bind_id) {
   timestamp_ = timestamp;
   thread_timestamp_ = thread_timestamp;
   duration_ = TimeDelta::FromInternalValue(-1);
@@ -607,6 +608,7 @@ void TraceEvent::Initialize(
   thread_id_ = thread_id;
   phase_ = phase;
   flags_ = flags;
+  bind_id_ = bind_id;
 
   // Clamp num_args since it may have been set by a third_party library.
   num_args = (num_args > kTraceMaxNumArgs) ? kTraceMaxNumArgs : num_args;
@@ -848,6 +850,16 @@ void TraceEvent::AppendAsJSON(
   if (flags_ & TRACE_EVENT_FLAG_BIND_TO_ENCLOSING)
     StringAppendF(out, ",\"bp\":\"e\"");
 
+  if (flags_ & TRACE_EVENT_FLAG_FLOW_OUT) {
+    StringAppendF(out, ",\"bind_id\":\"0x%" PRIx64 "\"", static_cast<uint64>(bind_id_));

[vmpstr, 2015/07/16 21:30:11]

why not just make the type uint64?

+    StringAppendF(out, ",\"dir\":\"o\"");
+  }
+
+  if (flags_ & TRACE_EVENT_FLAG_FLOW_IN) {
+    StringAppendF(out, ",\"bind_id\":\"0x%" PRIx64 "\"", static_cast<uint64>(bind_id_));
+    StringAppendF(out, ",\"dir\":\"i\"");
+  }
+
   // Instant events also output their scope.
   if (phase_ == TRACE_EVENT_PHASE_INSTANT) {
     char scope = '?';
@@ -1212,7 +1224,7 @@ void TraceLog::ThreadLocalEventBuffer::ReportOverhead(
           event_timestamp, event_thread_timestamp,
           TRACE_EVENT_PHASE_COMPLETE,
           &g_category_group_enabled[g_category_trace_event_overhead],
-          "overhead", 0, 0, NULL, NULL, NULL, NULL, 0);
+          "overhead", 0, 0, NULL, NULL, NULL, NULL, 0, 0);
       trace_event->UpdateDuration(now, thread_now);
     }
   }
@@ -2014,7 +2026,8 @@ TraceEventHandle TraceLog::AddTraceEvent(
                                                name, id, thread_id, now,
                                                num_args, arg_names,
                                                arg_types, arg_values,
-                                               convertable_values, flags);
+                                               convertable_values, flags,
+                                               trace_event_internal::kNoBindId);
 }
 
 TraceEventHandle TraceLog::AddTraceEventWithThreadIdAndTimestamp(
@@ -2029,7 +2042,8 @@ TraceEventHandle TraceLog::AddTraceEventWithThreadIdAndTimestamp(
     const unsigned char* arg_types,
     const unsigned long long* arg_values,
     const scoped_refptr<ConvertableToTraceFormat>* convertable_values,
-    unsigned int flags) {
+    unsigned int flags,
+    unsigned long long bind_id) {
   TraceEventHandle handle = { 0, 0, 0 };
   if (!*category_group_enabled)
     return handle;
@@ -2123,7 +2137,7 @@ TraceEventHandle TraceLog::AddTraceEventWithThreadIdAndTimestamp(
       trace_event->Initialize(thread_id, offset_event_timestamp, thread_now,
                               phase, category_group_enabled, name, id,
                               num_args, arg_names, arg_types, arg_values,
-                              convertable_values, flags);
+                              convertable_values, flags, bind_id);
 
 #if defined(OS_ANDROID)
       trace_event->SendToATrace();
@@ -2515,7 +2529,7 @@ ScopedTraceBinaryEfficient::ScopedTraceBinaryEfficient(
             trace_event_internal::kNoEventId,
             static_cast<int>(base::PlatformThread::CurrentId()),
             base::TraceTicks::Now(), 0, NULL, NULL, NULL, NULL,
-            TRACE_EVENT_FLAG_NONE);
+            TRACE_EVENT_FLAG_NONE, 0);
   }
 }