Adding raw tracing to trace framework.

base/debug/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 defines the set of functions necessary for trace_event_internal.h
 // to remain platform and context neutral.  To use tracing in another context,
 // copy this header (and trace_event_internal.h) and implement the
 // TRACE_EVENT_API_* macros below for the new environment.
 
 #ifndef BASE_DEBUG_TRACE_EVENT_H_
@@ skipping 18 matching lines @@
 //     TRACE_EVENT_API_GET_CATEGORY_ENABLED(const char* category_name)
 #define TRACE_EVENT_API_GET_CATEGORY_ENABLED \
     base::debug::TraceLog::GetCategoryEnabled
 
 // Add a trace event to the platform tracing system.
 // void TRACE_EVENT_API_ADD_TRACE_EVENT(
 //                    char phase,
 //                    const unsigned char* category_enabled,
 //                    const char* name,
 //                    unsigned long long id,
+//                    int thread_id,
+//                    int64 timestamp,

[jar (doing other things), 2013/02/14 02:17:54]

nit: This arg list as waaaay long, and it is saddening that there are a bunch of
ints in a row (easy to mix them up, and hard to read).  Have you considered
using a base::Time or a base::TimeTicks here?  Each would (under the covers) be
an int64 in a class, and would avoid any chance of confusing the argements.

[dsinclair, 2013/02/14 15:38:47]

Done.

 //                    int num_args,
 //                    const char** arg_names,
 //                    const unsigned char* arg_types,
 //                    const unsigned long long* arg_values,
 //                    unsigned char flags)
 #define TRACE_EVENT_API_ADD_TRACE_EVENT \
     base::debug::TraceLog::GetInstance()->AddTraceEvent
 
 // Defines atomic operations used internally by the tracing system.
 #define TRACE_EVENT_API_ATOMIC_WORD base::subtle::AtomicWord
 #define TRACE_EVENT_API_ATOMIC_LOAD(var) base::subtle::NoBarrier_Load(&(var))
 #define TRACE_EVENT_API_ATOMIC_STORE(var, value) \
     base::subtle::NoBarrier_Store(&(var), (value))
 
 // Defines visibility for classes in trace_event_internal.h
 #define TRACE_EVENT_API_CLASS_EXPORT BASE_EXPORT
 
 ////////////////////////////////////////////////////////////////////////////////
 
 #include "base/debug/trace_event_internal.h"
 
 #endif /* BASE_DEBUG_TRACE_EVENT_H_ */