Make non-scoped trace macros work in one-line scopes.

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 is designed to give you trace_event macros without specifying
 // how the events actually get collected and stored. If you need to expose trace
 // event to some other universe, you can copy-and-paste this file,
 // implement the TRACE_EVENT_API macros, and do any other necessary fixup for
 // the target platform. The end result is that multiple libraries can funnel
 // events through to a shared trace event collector.
@@ skipping 514 matching lines @@
       INTERNAL_TRACE_EVENT_UID(catstatic) = \
           TRACE_EVENT_API_GET_CATEGORY_ENABLED(category); \
       base::subtle::NoBarrier_Store(&INTERNAL_TRACE_EVENT_UID(atomic), \
           reinterpret_cast<base::subtle::AtomicWord>( \
               INTERNAL_TRACE_EVENT_UID(catstatic))); \
     }
 
 // Implementation detail: internal macro to create static category and add
 // event if the category is enabled.
 #define INTERNAL_TRACE_EVENT_ADD(phase, category, name, flags, ...) \
-    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
-    if (*INTERNAL_TRACE_EVENT_UID(catstatic)) { \
-      trace_event_internal::AddTraceEvent( \
-          phase, INTERNAL_TRACE_EVENT_UID(catstatic), name, \
-          trace_event_internal::kNoEventId, flags, ##__VA_ARGS__); \
-    }
+    do { \
+      INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
+      if (*INTERNAL_TRACE_EVENT_UID(catstatic)) { \
+        trace_event_internal::AddTraceEvent( \
+            phase, INTERNAL_TRACE_EVENT_UID(catstatic), name, \
+            trace_event_internal::kNoEventId, flags, ##__VA_ARGS__); \
+      } \
+    } while (0)
 
 // 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(category, name, ...) \
     INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
     trace_event_internal::TraceEndOnScopeClose \
         INTERNAL_TRACE_EVENT_UID(profileScope); \
     if (*INTERNAL_TRACE_EVENT_UID(catstatic)) { \
       trace_event_internal::AddTraceEvent( \
@@ skipping 22 matching lines @@
             TRACE_EVENT_FLAG_NONE, ##__VA_ARGS__); \
       INTERNAL_TRACE_EVENT_UID(profileScope).Initialize( \
           INTERNAL_TRACE_EVENT_UID(catstatic), name, \
           INTERNAL_TRACE_EVENT_UID(begin_event_id), threshold); \
     }
 
 // 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, name, id, flags, \
                                          ...) \
-    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
-    if (*INTERNAL_TRACE_EVENT_UID(catstatic)) { \
-      unsigned char trace_event_flags = flags | TRACE_EVENT_FLAG_HAS_ID; \
-      trace_event_internal::TraceID trace_event_trace_id( \
-          id, &trace_event_flags); \
-      trace_event_internal::AddTraceEvent( \
-          phase, INTERNAL_TRACE_EVENT_UID(catstatic), \
-          name, trace_event_trace_id.data(), trace_event_flags, \
-          ##__VA_ARGS__); \
-    }
+    do { \
+      INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
+      if (*INTERNAL_TRACE_EVENT_UID(catstatic)) { \
+        unsigned char trace_event_flags = flags | TRACE_EVENT_FLAG_HAS_ID; \
+        trace_event_internal::TraceID trace_event_trace_id( \
+            id, &trace_event_flags); \
+        trace_event_internal::AddTraceEvent( \
+            phase, INTERNAL_TRACE_EVENT_UID(catstatic), \
+            name, trace_event_trace_id.data(), trace_event_flags, \
+            ##__VA_ARGS__); \
+      } \
+    } while (0)
 
 // Notes regarding the following definitions:
 // New values can be added and propagated to third party libraries, but existing
 // definitions must never be changed, because third party libraries may use old
 // definitions.
 
 // Phase indicates the nature of an event entry. E.g. part of a begin/end pair.
 #define TRACE_EVENT_PHASE_BEGIN    ('B')
 #define TRACE_EVENT_PHASE_END      ('E')
 #define TRACE_EVENT_PHASE_INSTANT  ('I')
@@ skipping 256 matching lines @@
     const char* name;
     int threshold_begin_id;
   };
   Data* p_data_;
   Data data_;
 };
 
 }  // namespace trace_event_internal
 
 #endif  // BASE_DEBUG_TRACE_EVENT_H_