Tracing pre-filtering

base/trace_event/trace_log.h

 // Copyright 2015 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.
 
 #ifndef BASE_TRACE_EVENT_TRACE_LOG_H_
 #define BASE_TRACE_EVENT_TRACE_LOG_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 42 matching lines @@
   // The pointer returned from GetCategoryGroupEnabledInternal() points to a
   // value with zero or more of the following bits. Used in this class only.
   // The TRACE_EVENT macros should only use the value as a bool.
   // These values must be in sync with macro values in TraceEvent.h in Blink.
   enum CategoryGroupEnabledFlags {
     // Category group enabled for the recording mode.
     ENABLED_FOR_RECORDING = 1 << 0,
     // Category group enabled by SetEventCallbackEnabled().
     ENABLED_FOR_EVENT_CALLBACK = 1 << 2,
     // Category group enabled to export events to ETW.
-    ENABLED_FOR_ETW_EXPORT = 1 << 3
+    ENABLED_FOR_ETW_EXPORT = 1 << 3,
+    // TODO description
+    ENABLED_FOR_FILTERING = 1 << 4
   };
 
   static TraceLog* GetInstance();
 
   // Get set of known category groups. This can change as new code paths are
   // reached. The known category groups are inserted into |category_groups|.
   void GetKnownCategoryGroups(std::vector<std::string>* category_groups);
 
   // Retrieves a copy (for thread-safety) of the current TraceConfig.
   TraceConfig GetCurrentTraceConfig() const;
@@ skipping 423 matching lines @@
   subtle::AtomicWord generation_;
   bool use_worker_thread_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceLog);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_LOG_H_