[Tracing] Use TracingCategoryObserver in runtime statistics

src/tracing/trace-event.h

 // Copyright 2015 the V8 project 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 SRC_TRACING_TRACE_EVENT_H_
 #define SRC_TRACING_TRACE_EVENT_H_
 
 #include <stddef.h>
 #include <memory>
 
@@ skipping 231 matching lines @@
    private:                                                                \
     /* Local class friendly DISALLOW_COPY_AND_ASSIGN */                    \
     INTERNAL_TRACE_EVENT_UID(ScopedContext)                                \
     (const INTERNAL_TRACE_EVENT_UID(ScopedContext)&) {}                    \
     void operator=(const INTERNAL_TRACE_EVENT_UID(ScopedContext)&) {}      \
     uint64_t cid_;                                                         \
   };                                                                       \
   INTERNAL_TRACE_EVENT_UID(ScopedContext)                                  \
   INTERNAL_TRACE_EVENT_UID(scoped_context)(context);
 
-#define TRACE_EVENT_RUNTIME_CALL_STATS_TRACING_ENABLED() \
-  base::NoBarrier_Load(&v8::internal::tracing::kRuntimeCallStatsTracingEnabled)
-
 #define TRACE_EVENT_CALL_STATS_SCOPED(isolate, category_group, name) \
   INTERNAL_TRACE_EVENT_CALL_STATS_SCOPED(isolate, category_group, name)
 
 #define INTERNAL_TRACE_EVENT_CALL_STATS_SCOPED(isolate, category_group, name)  \
-  {                                                                            \
-    INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(                                    \
-        TRACE_DISABLED_BY_DEFAULT("v8.runtime_stats"));                        \
-    base::NoBarrier_Store(                                                     \
-        &v8::internal::tracing::kRuntimeCallStatsTracingEnabled,               \
-        INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE());     \
-  }                                                                            \
   INTERNAL_TRACE_EVENT_GET_CATEGORY_INFO(category_group);                      \
   v8::internal::tracing::CallStatsScopedTracer INTERNAL_TRACE_EVENT_UID(       \
       tracer);                                                                 \
   if (INTERNAL_TRACE_EVENT_CATEGORY_GROUP_ENABLED_FOR_RECORDING_MODE()) {      \
     INTERNAL_TRACE_EVENT_UID(tracer)                                           \
         .Initialize(isolate, INTERNAL_TRACE_EVENT_UID(category_group_enabled), \
                     name);                                                     \
   }
 
 namespace v8 {
@@ skipping 327 matching lines @@
   bool has_parent_scope_;
   Data* p_data_;
   Data data_;
 };
 
 }  // namespace tracing
 }  // namespace internal
 }  // namespace v8
 
 #endif  // SRC_TRACING_TRACE_EVENT_H_