Fix race in INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO

webrtc/base/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 under third_party_mods/chromium or at:
 // http://src.chromium.org/svn/trunk/src/LICENSE
 
 #ifndef WEBRTC_BASE_TRACE_EVENT_H_
 #define WEBRTC_BASE_TRACE_EVENT_H_
 
 #include <string>
 
@@ skipping 559 matching lines @@
 // variable a unique name based on the line number to prevent name collissions.
 #define INTERNAL_TRACE_EVENT_UID3(a,b) \
     trace_event_unique_##a##b
 #define INTERNAL_TRACE_EVENT_UID2(a,b) \
     INTERNAL_TRACE_EVENT_UID3(a,b)
 #define INTERNAL_TRACE_EVENT_UID(name_prefix) \
     INTERNAL_TRACE_EVENT_UID2(name_prefix, __LINE__)
 
 // Implementation detail: internal macro to create static category.
 #define INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category) \
-    static const unsigned char* INTERNAL_TRACE_EVENT_UID(catstatic) = 0; \
-    if (!INTERNAL_TRACE_EVENT_UID(catstatic)) { \
-      INTERNAL_TRACE_EVENT_UID(catstatic) = \
-          TRACE_EVENT_API_GET_CATEGORY_ENABLED(category); \
-    }
+    static const unsigned char* INTERNAL_TRACE_EVENT_UID(catstatic) = \
+        TRACE_EVENT_API_GET_CATEGORY_ENABLED(category);
 
 // 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, ...) \
     do { \
       INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category); \
       if (*INTERNAL_TRACE_EVENT_UID(catstatic)) { \
         webrtc::trace_event_internal::AddTraceEvent(          \
             phase, INTERNAL_TRACE_EVENT_UID(catstatic), name, \
             webrtc::trace_event_internal::kNoEventId, flags, ##__VA_ARGS__); \
@@ skipping 312 matching lines @@
     const char* name;
   };
   Data* p_data_;
   Data data_;
 };
 
 }  // namespace trace_event_internal
 }  // namespace webrtc
 
 #endif  // WEBRTC_BASE_TRACE_EVENT_H_