[tracing] Add trace events filtering predicate for heap profiler

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 296 matching lines @@
 
   // Exposed for unittesting:
 
   void WaitSamplingEventForTesting();
 
   // Allows deleting our singleton instance.
   static void DeleteForTesting();
 
   class TraceEventFilter {
    public:
+    static const char* const kEventWhitelistPredicate;
+    static const char* const kHeapProfilerPredicate;
+
     TraceEventFilter() {}
     virtual ~TraceEventFilter() {}
     virtual bool FilterTraceEvent(const TraceEvent& trace_event) const = 0;
     virtual void EndEvent(const char* category_group, const char* name) {}
 
    private:
     DISALLOW_COPY_AND_ASSIGN(TraceEventFilter);
   };
   typedef std::unique_ptr<TraceEventFilter> (
       *TraceEventFilterConstructorForTesting)(void);
@@ skipping 217 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_