Binds two IDs together.

base/trace_event/common/trace_event_common.h

Index: base/trace_event/common/trace_event_common.h
diff --git a/base/trace_event/common/trace_event_common.h b/base/trace_event/common/trace_event_common.h
index 0a04d627108c773755c5bdebf4fb897afc8d392f..03292eeca93ca184c370147a2540886d140b4671 100644
--- a/base/trace_event/common/trace_event_common.h
+++ b/base/trace_event/common/trace_event_common.h
@@ -987,6 +987,17 @@
   INTERNAL_TRACE_EVENT_SCOPED_CONTEXT(category_group, name,       \
                                       TRACE_ID_DONT_MANGLE(context))
 
+// Macro to specify that two trace IDs are identical. For example,
+// TRACE_BIND_IDS(
+//     "category", "name",
+//     TRACE_ID_WITH_SCOPE("net::URLRequest", 0x1000),
+//     TRACE_ID_WITH_SCOPE("blink::ResourceFetcher::FetchRequest", 0x2000))
+// tells the trace consumer that events with ID ("net::URLRequest", 0x1000) from
+// the current process have the same ID as events with ID
+// ("blink::ResourceFetcher::FetchRequest", 0x2000).
+#define TRACE_BIND_IDS(category_group, name, id, bind_id) \
+  INTERNAL_TRACE_EVENT_ADD_BIND_IDS(category_group, name, id, bind_id);
+
 // Macro to efficiently determine if a given category group is enabled.
 #define TRACE_EVENT_CATEGORY_GROUP_ENABLED(category_group, ret)             \
   do {                                                                      \
@@ -1052,6 +1063,7 @@
 #define TRACE_EVENT_PHASE_CLOCK_SYNC ('c')
 #define TRACE_EVENT_PHASE_ENTER_CONTEXT ('(')
 #define TRACE_EVENT_PHASE_LEAVE_CONTEXT (')')
+#define TRACE_EVENT_PHASE_BIND_IDS ('=')
 
 // Flags for changing the behavior of TRACE_EVENT_API_ADD_TRACE_EVENT.
 #define TRACE_EVENT_FLAG_NONE (static_cast<unsigned int>(0))