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

base/trace_event/trace_event_impl.h

Index: base/trace_event/trace_event_impl.h
diff --git a/base/trace_event/trace_event_impl.h b/base/trace_event/trace_event_impl.h
index a6e95f4152a039df5ac985ebad92423ef3a0a013..bd3e0402a030526ba52606f097e5b8faacb59076 100644
--- a/base/trace_event/trace_event_impl.h
+++ b/base/trace_event/trace_event_impl.h
@@ -121,7 +121,8 @@ class BASE_EXPORT TraceEvent {
       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);
 
   void Reset();
 
@@ -184,6 +185,7 @@ class BASE_EXPORT TraceEvent {
   int thread_id_;
   char phase_;
   unsigned int flags_;
+  unsigned long long bind_id_;
   unsigned char arg_types_[kTraceMaxNumArgs];
 
   DISALLOW_COPY_AND_ASSIGN(TraceEvent);
@@ -466,7 +468,8 @@ class BASE_EXPORT TraceLog : public MemoryDumpProvider {
       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);
   static void AddTraceEventEtw(char phase,
                                const char* category_group,
                                const void* id,