Revert of [counters] RuntimeStats: fix wrong bookkeeping when dynamically changing counters.

src/counters-inl.h

 // Copyright 2016 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 V8_COUNTERS_INL_H_
 #define V8_COUNTERS_INL_H_
 
 #include "src/counters.h"
 
 namespace v8 {
 namespace internal {
 
-void RuntimeCallTimer::Start(RuntimeCallCounter* counter,
-                             RuntimeCallTimer* parent) {
-  counter_ = counter;
-  parent_.SetValue(parent);
-  if (FLAG_runtime_stats !=
-      v8::tracing::TracingCategoryObserver::ENABLED_BY_SAMPLING) {
-    timer_.Start();
-  }
-}
-
-RuntimeCallTimer* RuntimeCallTimer::Stop() {
-  if (!timer_.IsStarted()) return parent();
-  base::TimeDelta delta = timer_.Elapsed();
-  timer_.Stop();
-  counter_->count++;
-  counter_->time += delta;
-  if (parent()) {
-    // Adjust parent timer so that it does not include sub timer's time.
-    parent()->Subtract(delta);
-  }
-  return parent();
-}
-
-void RuntimeCallTimer::Subtract(base::TimeDelta delta) {
-  // Adjust the current timer instead of directly subtracting the sub-timers
-  // from the current counter. This way we can easily change the counter of an
-  // active timer scope. Otherwise we would end up subtracting the time from the
-  // previous counter and add the own time to the newly changed counter.
-  timer_.Subtract(delta);
-}
-
-void RuntimeCallTimer::Snapshot() {
-  base::TimeTicks now = base::TimeTicks::HighResolutionNow();
-  RuntimeCallTimer* timer = this;
-  base::TimeDelta delta = base::TimeDelta::FromMicroseconds(0);
-  // Walk up the timer chain until the the timer doesn't have a parent.
-  while (timer != nullptr) {
-    // Iteration 1:   subtract 0 from the current timer (this).
-    // Iteration n+1: subtract subtimer's time (delta) from the the current
-    //                timer.
-    timer->Subtract(delta);
-    delta = timer->timer_.Restart(now);
-    timer->counter_->time += delta;
-    timer = timer->parent();
-  }
-}
-
 RuntimeCallTimerScope::RuntimeCallTimerScope(
     Isolate* isolate, RuntimeCallStats::CounterId counter_id) {
   if (V8_UNLIKELY(FLAG_runtime_stats)) {
     Initialize(isolate->counters()->runtime_call_stats(), counter_id);
   }
 }
 
 RuntimeCallTimerScope::RuntimeCallTimerScope(
     HeapObject* heap_object, RuntimeCallStats::CounterId counter_id) {
   RuntimeCallTimerScope(heap_object->GetIsolate(), counter_id);
 }
 
 RuntimeCallTimerScope::RuntimeCallTimerScope(
     RuntimeCallStats* stats, RuntimeCallStats::CounterId counter_id) {
   if (V8_UNLIKELY(FLAG_runtime_stats)) {
     Initialize(stats, counter_id);
   }
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COUNTERS_INL_H_