Add granular file tracing.

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.
 
 // This header file defines the set of trace_event macros without specifying
 // how the events actually get collected and stored. If you need to expose trace
 // events to some other universe, you can copy-and-paste this file as well as
 // trace_event.h, modifying the macros contained there as necessary for the
 // target platform. The end result is that multiple libraries can funnel events
 // through to a shared trace event collector.
@@ skipping 216 matching lines @@
     INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name)
 #define TRACE_EVENT1(category_group, name, arg1_name, arg1_val) \
     INTERNAL_TRACE_MEMORY(category_group, name) \
     INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name, arg1_name, arg1_val)
 #define TRACE_EVENT2( \
     category_group, name, arg1_name, arg1_val, arg2_name, arg2_val) \
   INTERNAL_TRACE_MEMORY(category_group, name) \
   INTERNAL_TRACE_EVENT_ADD_SCOPED( \
       category_group, name, arg1_name, arg1_val, arg2_name, arg2_val)
 
+// Records a pair of begin and end events called "name" for the current scope
+// with 1 or 2 associated arguments. These events are associated with id. If the
+// category is not enabled, this does nothing.
+// - category and name strings must have application lifetime (statics or
+//   literals). They may not include " chars.
+#define TRACE_EVENT_ID1(category_group, name, id, arg1_name, arg1_val) \
+  INTERNAL_TRACE_EVENT_ADD_SCOPED_WITH_ID( \
+      category_group, name, id, arg1_name, arg1_val)

[Sami, 2015/04/29 15:01:51]

It's not clear what |id| refers to here. Does it need to match the ASYNC id?

Could you upload a sample trace with this data in it just to get an idea of how
this looks? I'm wondering if the NESTABLE_ASYNC event would be more appropriate.

[Dan Beam, 2015/04/30 04:40:13]

yes
it probably is.  shared a TRACE_EVENT_ID* version with everybody (before I try
TRACE_EVENT_NESTABLE*).

+#define TRACE_EVENT_ID2( \
+    category_group, name, id, arg1_name, arg1_val, arg2_name, arg2_val) \
+  INTERNAL_TRACE_EVENT_ADD_SCOPED_WITH_ID( \
+      category_group, name, id, arg1_name, arg1_val, arg2_name, arg2_val)
+
 // Records events like TRACE_EVENT2 but uses |memory_tag| for memory tracing.
 // Use this where |name| is too generic to accurately aggregate allocations.
 #define TRACE_EVENT_WITH_MEMORY_TAG2( \
     category, name, memory_tag, arg1_name, arg1_val, arg2_name, arg2_val) \
   INTERNAL_TRACE_MEMORY(category, memory_tag) \
   INTERNAL_TRACE_EVENT_ADD_SCOPED( \
       category, name, arg1_name, arg1_val, arg2_name, arg2_val)
 
 // UNSHIPPED_TRACE_EVENT* are like TRACE_EVENT* except that they are not
 // included in official builds.
@@ skipping 755 matching lines @@
       base::trace_event::TraceEventHandle h = \
           trace_event_internal::AddTraceEvent( \
               TRACE_EVENT_PHASE_COMPLETE, \
               INTERNAL_TRACE_EVENT_UID(category_group_enabled), name, \
               trace_event_internal::kNoEventId, TRACE_EVENT_FLAG_NONE, \
               ##__VA_ARGS__); \
       INTERNAL_TRACE_EVENT_UID(tracer).Initialize( \
           INTERNAL_TRACE_EVENT_UID(category_group_enabled), name, h); \
     }
 
+// Implementation detail: internal macro to create static category and add begin
+// event if the category is enabled. Also adds the end event when the scope
+// ends.
+#define INTERNAL_TRACE_EVENT_ADD_SCOPED_WITH_ID(category_group, name, id, ...) \
+    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group); \
+    trace_event_internal::ScopedTracer INTERNAL_TRACE_EVENT_UID(tracer); \
+    if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
+      unsigned char trace_event_flags = TRACE_EVENT_FLAG_HAS_ID; \
+      trace_event_internal::TraceID trace_event_trace_id( \
+          id, &trace_event_flags); \
+      base::trace_event::TraceEventHandle h = \
+          trace_event_internal::AddTraceEvent( \
+              TRACE_EVENT_PHASE_COMPLETE, \
+              INTERNAL_TRACE_EVENT_UID(category_group_enabled), name, \
+              trace_event_trace_id.data(), trace_event_flags, \
+              ##__VA_ARGS__); \
+      INTERNAL_TRACE_EVENT_UID(tracer).Initialize( \
+          INTERNAL_TRACE_EVENT_UID(category_group_enabled), name, h); \
+    }
+
 // Implementation detail: internal macro to create static category and add
 // event if the category is enabled.
 #define INTERNAL_TRACE_EVENT_ADD_WITH_ID(phase, category_group, name, id, \
                                          flags, ...) \
     do { \
       INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group); \
       if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) { \
         unsigned char trace_event_flags = flags | TRACE_EVENT_FLAG_HAS_ID; \
         trace_event_internal::TraceID trace_event_trace_id( \
             id, &trace_event_flags); \
@@ skipping 611 matching lines @@
   const char* name_;
   IDType id_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceScopedTrackableObject);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_H_