Reland of [tracing] Fix, simplify and speed up accounting of TraceEvent memory overhead

base/trace_event/trace_event_impl.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.
 
 
 #ifndef BASE_TRACE_EVENT_TRACE_EVENT_IMPL_H_
 #define BASE_TRACE_EVENT_TRACE_EVENT_IMPL_H_
 
 #include <stack>
 #include <string>
@@ skipping 137 matching lines @@
 #endif
 
  private:
   // Note: these are ordered by size (largest first) for optimal packing.
   TraceTicks timestamp_;
   ThreadTicks thread_timestamp_;
   TimeDelta duration_;
   TimeDelta thread_duration_;
   // id_ can be used to store phase-specific data.
   unsigned long long id_;
-  scoped_ptr<TraceEventMemoryOverhead> cached_memory_overhead_estimate_;
   // context_id_ is used to store context information.
   unsigned long long context_id_;
   TraceValue arg_values_[kTraceMaxNumArgs];
   const char* arg_names_[kTraceMaxNumArgs];
   scoped_refptr<ConvertableToTraceFormat> convertable_values_[kTraceMaxNumArgs];
   const unsigned char* category_group_enabled_;
   const char* name_;
   scoped_refptr<base::RefCountedString> parameter_copy_storage_;
   int thread_id_;
   char phase_;
   unsigned int flags_;
   unsigned long long bind_id_;
   unsigned char arg_types_[kTraceMaxNumArgs];
 
   DISALLOW_COPY_AND_ASSIGN(TraceEvent);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_IMPL_H_