[heap] Introduce enum of garbage collection reasons.

src/heap/incremental-marking-job.cc

 // Copyright 2012 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.
 
 #include "src/heap/incremental-marking-job.h"
 
 #include "src/base/platform/time.h"
 #include "src/heap/heap-inl.h"
 #include "src/heap/heap.h"
 #include "src/heap/incremental-marking.h"
@@ skipping 66 matching lines @@
   if (incremental_marking->IsSweeping()) {
     incremental_marking->FinalizeSweeping();
     // TODO(hpayer): We can continue here if enough idle time is left.
     return kMoreWork;
   }
   const double remaining_idle_time_in_ms =
       incremental_marking->AdvanceIncrementalMarking(
           deadline_in_ms, IncrementalMarking::NO_GC_VIA_STACK_GUARD,
           IncrementalMarking::DO_NOT_FORCE_COMPLETION);
   if (remaining_idle_time_in_ms > 0.0) {
-    heap->TryFinalizeIdleIncrementalMarking(remaining_idle_time_in_ms);
+    heap->TryFinalizeIdleIncrementalMarking(
+        remaining_idle_time_in_ms,
+        GarbageCollectionReason::kFinalizeMarkingViaTask);
   }
   return incremental_marking->IsStopped() ? kDone : kMoreWork;
 }
 
 
 void IncrementalMarkingJob::IdleTask::RunInternal(double deadline_in_seconds) {
   double deadline_in_ms =
       deadline_in_seconds *
       static_cast<double>(base::Time::kMillisecondsPerSecond);
   Heap* heap = isolate()->heap();
@@ skipping 18 matching lines @@
 
 
 void IncrementalMarkingJob::DelayedTask::Step(Heap* heap) {
   const int kIncrementalMarkingDelayMs = 50;
   double deadline =
       heap->MonotonicallyIncreasingTimeInMs() + kIncrementalMarkingDelayMs;
   heap->incremental_marking()->AdvanceIncrementalMarking(
       deadline, IncrementalMarking::NO_GC_VIA_STACK_GUARD,
       IncrementalMarking::FORCE_COMPLETION);
   heap->FinalizeIncrementalMarkingIfComplete(
-      "Incremental marking task: finalize incremental marking");
+      GarbageCollectionReason::kFinalizeMarkingViaTask);
 }
 
 
 void IncrementalMarkingJob::DelayedTask::RunInternal() {
   Heap* heap = isolate()->heap();
   job_->NotifyDelayedTask();
   IncrementalMarking* incremental_marking = heap->incremental_marking();
   if (!incremental_marking->IsStopped()) {
     if (job_->ShouldForceMarkingStep()) {
       Step(heap);
     }
     // The Step() above could have finished incremental marking.
     if (!incremental_marking->IsStopped()) {
       job_->ScheduleDelayedTask(heap);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8